// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
 * Copyright (c) 2016 Facebook
 * Copyright (c) 2018 Covalent IO, Inc. http://covalent.io
 */
#include <uapi/linux/btf.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/bpf_verifier.h>
#include <linux/filter.h>
#include <net/netlink.h>
#include <linux/file.h>
#include <linux/vmalloc.h>
#include <linux/stringify.h>
#include <linux/bsearch.h>
#include <linux/sort.h>
#include <linux/perf_event.h>
#include <linux/ctype.h>
#include <linux/error-injection.h>
#include <linux/bpf_lsm.h>
#include <linux/btf_ids.h>

#include "disasm.h"

static const struct bpf_verifier_ops *const bpf_verifier_ops[] = {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) [_id] = &_name##_verifier_ops,
#define BPF_MAP_TYPE(_id, _ops)
#define BPF_LINK_TYPE(_id, _name)
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
#undef BPF_MAP_TYPE
#undef BPF_LINK_TYPE
};

/* bpf_check() is a static code analyzer that walks eBPF program
 * instruction by instruction and updates register/stack state.
 * All paths of conditional branches are analyzed until 'bpf_exit' insn.
 *
 * The first pass is depth-first-search to check that the program is a DAG.
 * It rejects the following programs:
 * - larger than BPF_MAXINSNS insns
 * - if loop is present (detected via back-edge)
 * - unreachable insns exist (shouldn't be a forest. program = one function)
 * - out of bounds or malformed jumps
 * The second pass is all possible path descent from the 1st insn.
 * Since it's analyzing all pathes through the program, the length of the
 * analysis is limited to 64k insn, which may be hit even if total number of
 * insn is less then 4K, but there are too many branches that change stack/regs.
 * Number of 'branches to be analyzed' is limited to 1k
 *
 * On entry to each instruction, each register has a type, and the instruction
 * changes the types of the registers depending on instruction semantics.
 * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
 * copied to R1.
 *
 * All registers are 64-bit.
 * R0 - return register
 * R1-R5 argument passing registers
 * R6-R9 callee saved registers
 * R10 - frame pointer read-only
 *
 * At the start of BPF program the register R1 contains a pointer to bpf_context
 * and has type PTR_TO_CTX.
 *
 * Verifier tracks arithmetic operations on pointers in case:
 *    BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
 *    BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
 * 1st insn copies R10 (which has FRAME_PTR) type into R1
 * and 2nd arithmetic instruction is pattern matched to recognize
 * that it wants to construct a pointer to some element within stack.
 * So after 2nd insn, the register R1 has type PTR_TO_STACK
 * (and -20 constant is saved for further stack bounds checking).
 * Meaning that this reg is a pointer to stack plus known immediate constant.
 *
 * Most of the time the registers have SCALAR_VALUE type, which
 * means the register has some value, but it's not a valid pointer.
 * (like pointer plus pointer becomes SCALAR_VALUE type)
 *
 * When verifier sees load or store instructions the type of base register
 * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK, PTR_TO_SOCKET. These are
 * four pointer types recognized by check_mem_access() function.
 *
 * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
 * and the range of [ptr, ptr + map's value_size) is accessible.
 *
 * registers used to pass values to function calls are checked against
 * function argument constraints.
 *
 * ARG_PTR_TO_MAP_KEY is one of such argument constraints.
 * It means that the register type passed to this function must be
 * PTR_TO_STACK and it will be used inside the function as
 * 'pointer to map element key'
 *
 * For example the argument constraints for bpf_map_lookup_elem():
 *   .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
 *   .arg1_type = ARG_CONST_MAP_PTR,
 *   .arg2_type = ARG_PTR_TO_MAP_KEY,
 *
 * ret_type says that this function returns 'pointer to map elem value or null'
 * function expects 1st argument to be a const pointer to 'struct bpf_map' and
 * 2nd argument should be a pointer to stack, which will be used inside
 * the helper function as a pointer to map element key.
 *
 * On the kernel side the helper function looks like:
 * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
 * {
 *    struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
 *    void *key = (void *) (unsigned long) r2;
 *    void *value;
 *
 *    here kernel can access 'key' and 'map' pointers safely, knowing that
 *    [key, key + map->key_size) bytes are valid and were initialized on
 *    the stack of eBPF program.
 * }
 *
 * Corresponding eBPF program may look like:
 *    BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),  // after this insn R2 type is FRAME_PTR
 *    BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
 *    BPF_LD_MAP_FD(BPF_REG_1, map_fd),      // after this insn R1 type is CONST_PTR_TO_MAP
 *    BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
 * here verifier looks at prototype of map_lookup_elem() and sees:
 * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
 * Now verifier knows that this map has key of R1->map_ptr->key_size bytes
 *
 * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
 * Now verifier checks that [R2, R2 + map's key_size) are within stack limits
 * and were initialized prior to this call.
 * If it's ok, then verifier allows this BPF_CALL insn and looks at
 * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
 * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
 * returns ether pointer to map value or NULL.
 *
 * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
 * insn, the register holding that pointer in the true branch changes state to
 * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
 * branch. See check_cond_jmp_op().
 *
 * After the call R0 is set to return type of the function and registers R1-R5
 * are set to NOT_INIT to indicate that they are no longer readable.
 *
 * The following reference types represent a potential reference to a kernel
 * resource which, after first being allocated, must be checked and freed by
 * the BPF program:
 * - PTR_TO_SOCKET_OR_NULL, PTR_TO_SOCKET
 *
 * When the verifier sees a helper call return a reference type, it allocates a
 * pointer id for the reference and stores it in the current function state.
 * Similar to the way that PTR_TO_MAP_VALUE_OR_NULL is converted into
 * PTR_TO_MAP_VALUE, PTR_TO_SOCKET_OR_NULL becomes PTR_TO_SOCKET when the type
 * passes through a NULL-check conditional. For the branch wherein the state is
 * changed to CONST_IMM, the verifier releases the reference.
 *
 * For each helper function that allocates a reference, such as
 * bpf_sk_lookup_tcp(), there is a corresponding release function, such as
 * bpf_sk_release(). When a reference type passes into the release function,
 * the verifier also releases the reference. If any unchecked or unreleased
 * reference remains at the end of the program, the verifier rejects it.
 */

/* verifier_state + insn_idx are pushed to stack when branch is encountered */
struct bpf_verifier_stack_elem {
    /* verifer state is 'st'
     * before processing instruction 'insn_idx'
     * and after processing instruction 'prev_insn_idx'
     */
    struct bpf_verifier_state st;
    int insn_idx;
    int prev_insn_idx;
    struct bpf_verifier_stack_elem *next;
    /* length of verifier log at the time this state was pushed on stack */
    u32 log_pos;
};

#define BPF_COMPLEXITY_LIMIT_JMP_SEQ 8192
#define BPF_COMPLEXITY_LIMIT_STATES 64

#define BPF_MAP_KEY_POISON (1ULL << 63)
#define BPF_MAP_KEY_SEEN (1ULL << 62)

#define BPF_MAP_PTR_UNPRIV 1UL
#define BPF_MAP_PTR_POISON ((void *)((0xeB9FUL << 1) + POISON_POINTER_DELTA))
#define BPF_MAP_PTR(X) ((struct bpf_map *)((X) & ~BPF_MAP_PTR_UNPRIV))

#define VERIFIER_TWO 2
#define VERIFIER_THREE 3
#define VERIFIER_FOUR 4
#define VERIFIER_EIGHT 8
#define VERIFIER_SIXTEEN 16
#define VERIFIER_THIRTYONE 31
#define VERIFIER_THIRTYTWO 32
#define VERIFIER_SIXTYTHREE 63
#define VERIFIER_SIXTYFOUR 64
#define VERIFIER_ONEHUNDREDTWENTYEIGHT 128
#define VERIFIER_TWOHUNDREDFIFTYSIX 256
#define VERIFIER_ONETHOUSAND 1000

static bool bpf_map_ptr_poisoned(const struct bpf_insn_aux_data *aux)
{
    return BPF_MAP_PTR(aux->map_ptr_state) == BPF_MAP_PTR_POISON;
}

static bool bpf_map_ptr_unpriv(const struct bpf_insn_aux_data *aux)
{
    return aux->map_ptr_state & BPF_MAP_PTR_UNPRIV;
}

static void bpf_map_ptr_store(struct bpf_insn_aux_data *aux, const struct bpf_map *map, bool unpriv)
{
    BUILD_BUG_ON((unsigned long)BPF_MAP_PTR_POISON & BPF_MAP_PTR_UNPRIV);
    unpriv |= bpf_map_ptr_unpriv(aux);
    aux->map_ptr_state = (unsigned long)map | (unpriv ? BPF_MAP_PTR_UNPRIV : 0UL);
}

static bool bpf_map_key_poisoned(const struct bpf_insn_aux_data *aux)
{
    return aux->map_key_state & BPF_MAP_KEY_POISON;
}

static bool bpf_map_key_unseen(const struct bpf_insn_aux_data *aux)
{
    return !(aux->map_key_state & BPF_MAP_KEY_SEEN);
}

static u64 bpf_map_key_immediate(const struct bpf_insn_aux_data *aux)
{
    return aux->map_key_state & ~(BPF_MAP_KEY_SEEN | BPF_MAP_KEY_POISON);
}

static void bpf_map_key_store(struct bpf_insn_aux_data *aux, u64 state)
{
    bool poisoned = bpf_map_key_poisoned(aux);

    aux->map_key_state = state | BPF_MAP_KEY_SEEN | (poisoned ? BPF_MAP_KEY_POISON : 0ULL);
}

struct bpf_call_arg_meta {
    struct bpf_map *map_ptr;
    bool raw_mode;
    bool pkt_access;
    int regno;
    int access_size;
    int mem_size;
    u64 msize_max_value;
    int ref_obj_id;
    int func_id;
    u32 btf_id;
    u32 ret_btf_id;
};

struct btf *btf_vmlinux;

static DEFINE_MUTEX(bpf_verifier_lock);

static const struct bpf_line_info *find_linfo(const struct bpf_verifier_env *env, u32 insn_off)
{
    const struct bpf_line_info *linfo;
    const struct bpf_prog *prog;
    u32 i, nr_linfo;

    prog = env->prog;
    nr_linfo = prog->aux->nr_linfo;

    if (!nr_linfo || insn_off >= prog->len) {
        return NULL;
    }

    linfo = prog->aux->linfo;
    for (i = 1; i < nr_linfo; i++) {
        if (insn_off < linfo[i].insn_off) {
            break;
        }
    }

    return &linfo[i - 1];
}

void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt, va_list args)
{
    unsigned int n;

    n = vscnprintf(log->kbuf, BPF_VERIFIER_TMP_LOG_SIZE, fmt, args);

    WARN_ONCE(n >= BPF_VERIFIER_TMP_LOG_SIZE - 1, "verifier log line truncated - local buffer too short\n");

    n = min(log->len_total - log->len_used - 1, n);
    log->kbuf[n] = '\0';

    if (log->level == BPF_LOG_KERNEL) {
        pr_err("BPF:%s\n", log->kbuf);
        return;
    }
    if (!copy_to_user(log->ubuf + log->len_used, log->kbuf, n + 1)) {
        log->len_used += n;
    } else {
        log->ubuf = NULL;
    }
}

static void bpf_vlog_reset(struct bpf_verifier_log *log, u32 new_pos)
{
    char zero = 0;

    if (!bpf_verifier_log_needed(log)) {
        return;
    }

    log->len_used = new_pos;
    if (put_user(zero, log->ubuf + new_pos)) {
        log->ubuf = NULL;
    }
}

/* log_level controls verbosity level of eBPF verifier.
 * bpf_verifier_log_write() is used to dump the verification trace to the log,
 * so the user can figure out what's wrong with the program
 */
__printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env, const char *fmt, ...)
{
    va_list args;

    if (!bpf_verifier_log_needed(&env->log)) {
        return;
    }

    va_start(args, fmt);
    bpf_verifier_vlog(&env->log, fmt, args);
    va_end(args);
}
EXPORT_SYMBOL_GPL(bpf_verifier_log_write);

__printf(2, 3) static void verbose(void *private_data, const char *fmt, ...)
{
    struct bpf_verifier_env *env = private_data;
    va_list args;

    if (!bpf_verifier_log_needed(&env->log)) {
        return;
    }

    va_start(args, fmt);
    bpf_verifier_vlog(&env->log, fmt, args);
    va_end(args);
}

__printf(2, 3) void bpf_log(struct bpf_verifier_log *log, const char *fmt, ...)
{
    va_list args;

    if (!bpf_verifier_log_needed(log)) {
        return;
    }

    va_start(args, fmt);
    bpf_verifier_vlog(log, fmt, args);
    va_end(args);
}

static const char *ltrim(const char *s)
{
    while (isspace(*s)) {
        s++;
    }

    return s;
}

__printf(3, 4) static void verbose_linfo(struct bpf_verifier_env *env, u32 insn_off, const char *prefix_fmt, ...)
{
    const struct bpf_line_info *linfo;

    if (!bpf_verifier_log_needed(&env->log)) {
        return;
    }

    linfo = find_linfo(env, insn_off);
    if (!linfo || linfo == env->prev_linfo) {
        return;
    }

    if (prefix_fmt) {
        va_list args;

        va_start(args, prefix_fmt);
        bpf_verifier_vlog(&env->log, prefix_fmt, args);
        va_end(args);
    }

    verbose(env, "%s\n", ltrim(btf_name_by_offset(env->prog->aux->btf, linfo->line_off)));

    env->prev_linfo = linfo;
}

static bool type_is_pkt_pointer(enum bpf_reg_type type)
{
    return type == PTR_TO_PACKET || type == PTR_TO_PACKET_META;
}

static bool type_is_sk_pointer(enum bpf_reg_type type)
{
    return type == PTR_TO_SOCKET || type == PTR_TO_SOCK_COMMON || type == PTR_TO_TCP_SOCK || type == PTR_TO_XDP_SOCK;
}

static bool reg_type_not_null(enum bpf_reg_type type)
{
    return type == PTR_TO_SOCKET || type == PTR_TO_TCP_SOCK || type == PTR_TO_MAP_VALUE || type == PTR_TO_SOCK_COMMON;
}

static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg)
{
    return reg->type == PTR_TO_MAP_VALUE && map_value_has_spin_lock(reg->map_ptr);
}

static bool reg_type_may_be_refcounted_or_null(enum bpf_reg_type type)
{
    return base_type(type) == PTR_TO_SOCKET || base_type(type) == PTR_TO_TCP_SOCK || base_type(type) == PTR_TO_MEM;
}

static bool type_is_rdonly_mem(u32 type)
{
    return type & MEM_RDONLY;
}

static bool arg_type_may_be_refcounted(enum bpf_arg_type type)
{
    return type == ARG_PTR_TO_SOCK_COMMON;
}

static bool type_may_be_null(u32 type)
{
    return type & PTR_MAYBE_NULL;
}

/* Determine whether the function releases some resources allocated by another
 * function call. The first reference type argument will be assumed to be
 * released by release_reference().
 */
static bool is_release_function(enum bpf_func_id func_id)
{
    return func_id == BPF_FUNC_sk_release || func_id == BPF_FUNC_ringbuf_submit || func_id == BPF_FUNC_ringbuf_discard;
}

static bool may_be_acquire_function(enum bpf_func_id func_id)
{
    return func_id == BPF_FUNC_sk_lookup_tcp || func_id == BPF_FUNC_sk_lookup_udp ||
           func_id == BPF_FUNC_skc_lookup_tcp || func_id == BPF_FUNC_map_lookup_elem ||
           func_id == BPF_FUNC_ringbuf_reserve;
}

static bool is_acquire_function(enum bpf_func_id func_id, const struct bpf_map *map)
{
    enum bpf_map_type map_type = map ? map->map_type : BPF_MAP_TYPE_UNSPEC;

    if (func_id == BPF_FUNC_sk_lookup_tcp || func_id == BPF_FUNC_sk_lookup_udp || func_id == BPF_FUNC_skc_lookup_tcp ||
        func_id == BPF_FUNC_ringbuf_reserve) {
        return true;
    }

    if (func_id == BPF_FUNC_map_lookup_elem &&
        (map_type == BPF_MAP_TYPE_SOCKMAP || map_type == BPF_MAP_TYPE_SOCKHASH)) {
        return true;
    }

    return false;
}

static bool is_ptr_cast_function(enum bpf_func_id func_id)
{
    return func_id == BPF_FUNC_tcp_sock || func_id == BPF_FUNC_sk_fullsock || func_id == BPF_FUNC_skc_to_tcp_sock ||
           func_id == BPF_FUNC_skc_to_tcp6_sock || func_id == BPF_FUNC_skc_to_udp6_sock ||
           func_id == BPF_FUNC_skc_to_tcp_timewait_sock || func_id == BPF_FUNC_skc_to_tcp_request_sock;
}

/* string representation of 'enum bpf_reg_type'
 *
 * Note that reg_type_str() can not appear more than once in a single verbose()
 * statement.
 */
static const char *reg_type_str(struct bpf_verifier_env *env, enum bpf_reg_type type)
{
    char postfix[VERIFIER_SIXTEEN] = {0}, prefix[VERIFIER_SIXTEEN] = {0};
    static const char *const str[] = {
        [NOT_INIT] = "?",
        [SCALAR_VALUE] = "inv",
        [PTR_TO_CTX] = "ctx",
        [CONST_PTR_TO_MAP] = "map_ptr",
        [PTR_TO_MAP_VALUE] = "map_value",
        [PTR_TO_STACK] = "fp",
        [PTR_TO_PACKET] = "pkt",
        [PTR_TO_PACKET_META] = "pkt_meta",
        [PTR_TO_PACKET_END] = "pkt_end",
        [PTR_TO_FLOW_KEYS] = "flow_keys",
        [PTR_TO_SOCKET] = "sock",
        [PTR_TO_SOCK_COMMON] = "sock_common",
        [PTR_TO_TCP_SOCK] = "tcp_sock",
        [PTR_TO_TP_BUFFER] = "tp_buffer",
        [PTR_TO_XDP_SOCK] = "xdp_sock",
        [PTR_TO_BTF_ID] = "ptr_",
        [PTR_TO_PERCPU_BTF_ID] = "percpu_ptr_",
        [PTR_TO_MEM] = "mem",
        [PTR_TO_BUF] = "buf",
    };

    if (type & PTR_MAYBE_NULL) {
        if (base_type(type) == PTR_TO_BTF_ID || base_type(type) == PTR_TO_PERCPU_BTF_ID) {
            strncpy(postfix, "or_null_", VERIFIER_SIXTEEN);
        } else {
            strncpy(postfix, "_or_null", VERIFIER_SIXTEEN);
        }
    }

    if (type & MEM_RDONLY) {
        strncpy(prefix, "rdonly_", VERIFIER_SIXTEEN);
    }
    if (type & MEM_ALLOC) {
        strncpy(prefix, "alloc_", VERIFIER_SIXTEEN);
    }

    (void)snprintf(env->type_str_buf, TYPE_STR_BUF_LEN, "%s%s%s", prefix, str[base_type(type)], postfix);
    return env->type_str_buf;
}

static char slot_type_char[] = {
    [STACK_INVALID] = '?',
    [STACK_SPILL] = 'r',
    [STACK_MISC] = 'm',
    [STACK_ZERO] = '0',
};

static void print_liveness(struct bpf_verifier_env *env, enum bpf_reg_liveness live)
{
    if (live & (REG_LIVE_READ | REG_LIVE_WRITTEN | REG_LIVE_DONE)) {
        verbose(env, "_");
    }
    if (live & REG_LIVE_READ) {
        verbose(env, "r");
    }
    if (live & REG_LIVE_WRITTEN) {
        verbose(env, "w");
    }
    if (live & REG_LIVE_DONE) {
        verbose(env, "D");
    }
}

static struct bpf_func_state *func(struct bpf_verifier_env *env, const struct bpf_reg_state *reg)
{
    struct bpf_verifier_state *cur = env->cur_state;

    return cur->frame[reg->frameno];
}

const char *kernel_type_name(u32 id)
{
    return btf_name_by_offset(btf_vmlinux, btf_type_by_id(btf_vmlinux, id)->name_off);
}

static void print_verifier_state(struct bpf_verifier_env *env, const struct bpf_func_state *state)
{
    const struct bpf_reg_state *reg;
    enum bpf_reg_type t;
    int i;

    if (state->frameno) {
        verbose(env, " frame%d:", state->frameno);
    }
    for (i = 0; i < MAX_BPF_REG; i++) {
        reg = &state->regs[i];
        t = reg->type;
        if (t == NOT_INIT) {
            continue;
        }
        verbose(env, " R%d", i);
        print_liveness(env, reg->live);
        verbose(env, "=%s", reg_type_str(env, t));
        if (t == SCALAR_VALUE && reg->precise) {
            verbose(env, "P");
        }
        if ((t == SCALAR_VALUE || t == PTR_TO_STACK) && tnum_is_const(reg->var_off)) {
            /* reg->off should be 0 for SCALAR_VALUE */
            verbose(env, "%lld", reg->var_off.value + reg->off);
        } else {
            if (base_type(t) == PTR_TO_BTF_ID || base_type(t) == PTR_TO_PERCPU_BTF_ID) {
                verbose(env, "%s", kernel_type_name(reg->btf_id));
            }
            verbose(env, "(id=%d", reg->id);
            if (reg_type_may_be_refcounted_or_null(t)) {
                verbose(env, ",ref_obj_id=%d", reg->ref_obj_id);
            }
            if (t != SCALAR_VALUE) {
                verbose(env, ",off=%d", reg->off);
            }
            if (type_is_pkt_pointer(t)) {
                verbose(env, ",r=%d", reg->range);
            } else if (base_type(t) == CONST_PTR_TO_MAP || base_type(t) == PTR_TO_MAP_VALUE) {
                verbose(env, ",ks=%d,vs=%d", reg->map_ptr->key_size, reg->map_ptr->value_size);
            }
            if (tnum_is_const(reg->var_off)) {
                /* Typically an immediate SCALAR_VALUE, but
                 * could be a pointer whose offset is too big
                 * for reg->off
                 */
                verbose(env, ",imm=%llx", reg->var_off.value);
            } else {
                if (reg->smin_value != reg->umin_value && reg->smin_value != S64_MIN) {
                    verbose(env, ",smin_value=%lld", (long long)reg->smin_value);
                }
                if (reg->smax_value != reg->umax_value && reg->smax_value != S64_MAX) {
                    verbose(env, ",smax_value=%lld", (long long)reg->smax_value);
                }
                if (reg->umin_value != 0) {
                    verbose(env, ",umin_value=%llu", (unsigned long long)reg->umin_value);
                }
                if (reg->umax_value != U64_MAX) {
                    verbose(env, ",umax_value=%llu", (unsigned long long)reg->umax_value);
                }
                if (!tnum_is_unknown(reg->var_off)) {
                    char tn_buf[48];

                    tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
                    verbose(env, ",var_off=%s", tn_buf);
                }
                if (reg->s32_min_value != reg->smin_value && reg->s32_min_value != S32_MIN) {
                    verbose(env, ",s32_min_value=%d", (int)(reg->s32_min_value));
                }
                if (reg->s32_max_value != reg->smax_value && reg->s32_max_value != S32_MAX) {
                    verbose(env, ",s32_max_value=%d", (int)(reg->s32_max_value));
                }
                if (reg->u32_min_value != reg->umin_value && reg->u32_min_value != U32_MIN) {
                    verbose(env, ",u32_min_value=%d", (int)(reg->u32_min_value));
                }
                if (reg->u32_max_value != reg->umax_value && reg->u32_max_value != U32_MAX) {
                    verbose(env, ",u32_max_value=%d", (int)(reg->u32_max_value));
                }
            }
            verbose(env, ")");
        }
    }
    for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
        char types_buf[BPF_REG_SIZE + 1];
        bool valid = false;
        int j;

        for (j = 0; j < BPF_REG_SIZE; j++) {
            if (state->stack[i].slot_type[j] != STACK_INVALID) {
                valid = true;
            }
            types_buf[j] = slot_type_char[state->stack[i].slot_type[j]];
        }
        types_buf[BPF_REG_SIZE] = 0;
        if (!valid) {
            continue;
        }
        verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE);
        print_liveness(env, state->stack[i].spilled_ptr.live);
        if (state->stack[i].slot_type[0] == STACK_SPILL) {
            reg = &state->stack[i].spilled_ptr;
            t = reg->type;
            verbose(env, "=%s", reg_type_str(env, t));
            if (t == SCALAR_VALUE && reg->precise) {
                verbose(env, "P");
            }
            if (t == SCALAR_VALUE && tnum_is_const(reg->var_off)) {
                verbose(env, "%lld", reg->var_off.value + reg->off);
            }
        } else {
            verbose(env, "=%s", types_buf);
        }
    }
    if (state->acquired_refs && state->refs[0].id) {
        verbose(env, " refs=%d", state->refs[0].id);
        for (i = 1; i < state->acquired_refs; i++) {
            if (state->refs[i].id) {
                verbose(env, ",%d", state->refs[i].id);
            }
        }
    }
    verbose(env, "\n");
}

#define COPY_STATE_FN(NAME, COUNT, FIELD, SIZE)                                                                        \
    static int copy_##NAME##_state(struct bpf_func_state *dst, const struct bpf_func_state *src)                       \
    {                                                                                                                  \
        if (!src->FIELD)                                                                                               \
            return 0;                                                                                                  \
        if (WARN_ON_ONCE(dst->COUNT < src->COUNT)) {                                                                   \
            /* internal bug, make state invalid to reject the program */                                               \
            memset(dst, 0, sizeof(*dst));                                                                              \
            return -EFAULT;                                                                                            \
        }                                                                                                              \
        memcpy(dst->FIELD, src->FIELD, sizeof(*src->FIELD) * (src->COUNT / (SIZE)));                                   \
        return 0;                                                                                                      \
    }
/* copy_reference_state() */
COPY_STATE_FN(reference, acquired_refs, refs, 1)
/* copy_stack_state() */
COPY_STATE_FN(stack, allocated_stack, stack, BPF_REG_SIZE)
#undef COPY_STATE_FN

#define REALLOC_STATE_FN(NAME, COUNT, FIELD, SIZE)                                                                     \
    static int realloc_##NAME##_state(struct bpf_func_state *state, int size, bool copy_old)                           \
    {                                                                                                                  \
        u32 old_size = state->COUNT;                                                                                   \
        struct bpf_##NAME##_state *new_##FIELD;                                                                        \
        int slot = size / (SIZE);                                                                                      \
                                                                                                                       \
        if (size <= old_size || !size) {                                                                               \
            if (copy_old)                                                                                              \
                return 0;                                                                                              \
            state->COUNT = slot * (SIZE);                                                                              \
            if (!size && old_size) {                                                                                   \
                kfree(state->FIELD);                                                                                   \
                state->FIELD = NULL;                                                                                   \
            }                                                                                                          \
            return 0;                                                                                                  \
        }                                                                                                              \
        new_##FIELD = kmalloc_array(slot, sizeof(struct bpf_##NAME##_state), GFP_KERNEL);                              \
        if (!new_##FIELD)                                                                                              \
            return -ENOMEM;                                                                                            \
        if (copy_old) {                                                                                                \
            if (state->FIELD)                                                                                          \
                memcpy(new_##FIELD, state->FIELD, sizeof(*new_##FIELD) * (old_size / (SIZE)));                         \
            memset(new_##FIELD + old_size / (SIZE), 0, sizeof(*new_##FIELD) * (size - old_size) / (SIZE));             \
        }                                                                                                              \
        state->COUNT = slot * (SIZE);                                                                                  \
        kfree(state->FIELD);                                                                                           \
        state->FIELD = new_##FIELD;                                                                                    \
        return 0;                                                                                                      \
    }
/* realloc_reference_state() */
REALLOC_STATE_FN(reference, acquired_refs, refs, 1)
/* realloc_stack_state() */
REALLOC_STATE_FN(stack, allocated_stack, stack, BPF_REG_SIZE)
#undef REALLOC_STATE_FN

/* do_check() starts with zero-sized stack in struct bpf_verifier_state to
 * make it consume minimal amount of memory. check_stack_write() access from
 * the program calls into realloc_func_state() to grow the stack size.
 * Note there is a non-zero 'parent' pointer inside bpf_verifier_state
 * which realloc_stack_state() copies over. It points to previous
 * bpf_verifier_state which is never reallocated.
 */
static int realloc_func_state(struct bpf_func_state *state, int stack_size, int refs_size, bool copy_old)
{
    int err = realloc_reference_state(state, refs_size, copy_old);
    if (err) {
        return err;
    }
    return realloc_stack_state(state, stack_size, copy_old);
}

/* Acquire a pointer id from the env and update the state->refs to include
 * this new pointer reference.
 * On success, returns a valid pointer id to associate with the register
 * On failure, returns a negative errno.
 */
static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx)
{
    struct bpf_func_state *state = cur_func(env);
    int new_ofs = state->acquired_refs;
    int id, err;

    err = realloc_reference_state(state, state->acquired_refs + 1, true);
    if (err) {
        return err;
    }
    id = ++env->id_gen;
    state->refs[new_ofs].id = id;
    state->refs[new_ofs].insn_idx = insn_idx;

    return id;
}

/* release function corresponding to acquire_reference_state(). Idempotent. */
static int release_reference_state(struct bpf_func_state *state, int ptr_id)
{
    int i, last_idx;

    last_idx = state->acquired_refs - 1;
    for (i = 0; i < state->acquired_refs; i++) {
        if (state->refs[i].id == ptr_id) {
            if (last_idx && i != last_idx) {
                memcpy(&state->refs[i], &state->refs[last_idx], sizeof(*state->refs));
            }
            memset(&state->refs[last_idx], 0, sizeof(*state->refs));
            state->acquired_refs--;
            return 0;
        }
    }
    return -EINVAL;
}

static int transfer_reference_state(struct bpf_func_state *dst, struct bpf_func_state *src)
{
    int err = realloc_reference_state(dst, src->acquired_refs, false);
    if (err) {
        return err;
    }
    err = copy_reference_state(dst, src);
    if (err) {
        return err;
    }
    return 0;
}

static void free_func_state(struct bpf_func_state *state)
{
    if (!state) {
        return;
    }
    kfree(state->refs);
    kfree(state->stack);
    kfree(state);
}

static void clear_jmp_history(struct bpf_verifier_state *state)
{
    kfree(state->jmp_history);
    state->jmp_history = NULL;
    state->jmp_history_cnt = 0;
}

static void free_verifier_state(struct bpf_verifier_state *state, bool free_self)
{
    int i;

    for (i = 0; i <= state->curframe; i++) {
        free_func_state(state->frame[i]);
        state->frame[i] = NULL;
    }
    clear_jmp_history(state);
    if (free_self) {
        kfree(state);
    }
}

/* copy verifier state from src to dst growing dst stack space
 * when necessary to accommodate larger src stack
 */
static int copy_func_state(struct bpf_func_state *dst, const struct bpf_func_state *src)
{
    int err;

    err = realloc_func_state(dst, src->allocated_stack, src->acquired_refs, false);
    if (err) {
        return err;
    }
    memcpy(dst, src, offsetof(struct bpf_func_state, acquired_refs));
    err = copy_reference_state(dst, src);
    if (err) {
        return err;
    }
    return copy_stack_state(dst, src);
}

static int copy_verifier_state(struct bpf_verifier_state *dst_state, const struct bpf_verifier_state *src)
{
    struct bpf_func_state *dst;
    u32 jmp_sz = sizeof(struct bpf_idx_pair) * src->jmp_history_cnt;
    int i, err;

    if (dst_state->jmp_history_cnt < src->jmp_history_cnt) {
        kfree(dst_state->jmp_history);
        dst_state->jmp_history = kmalloc(jmp_sz, GFP_USER);
        if (!dst_state->jmp_history) {
            return -ENOMEM;
        }
    }
    memcpy(dst_state->jmp_history, src->jmp_history, jmp_sz);
    dst_state->jmp_history_cnt = src->jmp_history_cnt;

    /* if dst has more stack frames then src frame, free them */
    for (i = src->curframe + 1; i <= dst_state->curframe; i++) {
        free_func_state(dst_state->frame[i]);
        dst_state->frame[i] = NULL;
    }
    dst_state->speculative = src->speculative;
    dst_state->curframe = src->curframe;
    dst_state->active_spin_lock = src->active_spin_lock;
    dst_state->branches = src->branches;
    dst_state->parent = src->parent;
    dst_state->first_insn_idx = src->first_insn_idx;
    dst_state->last_insn_idx = src->last_insn_idx;
    for (i = 0; i <= src->curframe; i++) {
        dst = dst_state->frame[i];
        if (!dst) {
            dst = kzalloc(sizeof(*dst), GFP_KERNEL);
            if (!dst) {
                return -ENOMEM;
            }
            dst_state->frame[i] = dst;
        }
        err = copy_func_state(dst, src->frame[i]);
        if (err) {
            return err;
        }
    }
    return 0;
}

static void update_branch_counts(struct bpf_verifier_env *env, struct bpf_verifier_state *st)
{
    while (st) {
        u32 br = --st->branches;

        /* WARN_ON(br > 1) technically makes sense here,
         * but see comment in push_stack(), hence:
         */
        WARN_ONCE((int)br < 0, "BUG update_branch_counts:branches_to_explore=%d\n", br);
        if (br) {
            break;
        }
        st = st->parent;
    }
}

static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx, int *insn_idx, bool pop_log)
{
    struct bpf_verifier_state *cur = env->cur_state;
    struct bpf_verifier_stack_elem *elem, *head = env->head;
    int err;

    if (env->head == NULL) {
        return -ENOENT;
    }

    if (cur) {
        err = copy_verifier_state(cur, &head->st);
        if (err) {
            return err;
        }
    }
    if (pop_log) {
        bpf_vlog_reset(&env->log, head->log_pos);
    }
    if (insn_idx) {
        *insn_idx = head->insn_idx;
    }
    if (prev_insn_idx) {
        *prev_insn_idx = head->prev_insn_idx;
    }
    elem = head->next;
    free_verifier_state(&head->st, false);
    kfree(head);
    env->head = elem;
    env->stack_size--;
    return 0;
}

static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env, int insn_idx, int prev_insn_idx,
                                             bool speculative)
{
    struct bpf_verifier_state *cur = env->cur_state;
    struct bpf_verifier_stack_elem *elem;
    int err;

    elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
    if (!elem) {
        goto err;
    }

    elem->insn_idx = insn_idx;
    elem->prev_insn_idx = prev_insn_idx;
    elem->next = env->head;
    elem->log_pos = env->log.len_used;
    env->head = elem;
    env->stack_size++;
    err = copy_verifier_state(&elem->st, cur);
    if (err) {
        goto err;
    }
    elem->st.speculative |= speculative;
    if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) {
        verbose(env, "The sequence of %d jumps is too complex.\n", env->stack_size);
        goto err;
    }
    if (elem->st.parent) {
        ++elem->st.parent->branches;
        /* WARN_ON(branches > 2) technically makes sense here,
         * but
         * 1. speculative states will bump 'branches' for non-branch
         * instructions
         * 2. is_state_visited() heuristics may decide not to create
         * a new state for a sequence of branches and all such current
         * and cloned states will be pointing to a single parent state
         * which might have large 'branches' count.
         */
    }
    return &elem->st;
err:
    free_verifier_state(env->cur_state, true);
    env->cur_state = NULL;
    /* pop all elements and return */
    while (!pop_stack(env, NULL, NULL, false)) {
        ;
    }
    return NULL;
}

#define CALLER_SAVED_REGS 6
static const int caller_saved[CALLER_SAVED_REGS] = {BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5};

static void verifier_mark_reg_not_init(const struct bpf_verifier_env *env, struct bpf_reg_state *reg);

/* This helper doesn't clear reg->id */
static void verifier2_mark_reg_known(struct bpf_reg_state *reg, u64 imm)
{
    reg->var_off = tnum_const(imm);
    reg->smin_value = (s64)imm;
    reg->smax_value = (s64)imm;
    reg->umin_value = imm;
    reg->umax_value = imm;

    reg->s32_min_value = (s32)imm;
    reg->s32_max_value = (s32)imm;
    reg->u32_min_value = (u32)imm;
    reg->u32_max_value = (u32)imm;
}

/* Mark the unknown part of a register (variable offset or scalar value) as
 * known to have the value @imm.
 */
static void verifier_mark_reg_known(struct bpf_reg_state *reg, u64 imm)
{
    /* Clear id, off, and union(map_ptr, range) */
    memset(((u8 *)reg) + sizeof(reg->type), 0, offsetof(struct bpf_reg_state, var_off) - sizeof(reg->type));
    verifier2_mark_reg_known(reg, imm);
}

static void verifier_mark_reg32_known(struct bpf_reg_state *reg, u64 imm)
{
    reg->var_off = tnum_const_subreg(reg->var_off, imm);
    reg->s32_min_value = (s32)imm;
    reg->s32_max_value = (s32)imm;
    reg->u32_min_value = (u32)imm;
    reg->u32_max_value = (u32)imm;
}

/* Mark the 'variable offset' part of a register as zero.  This should be
 * used only on registers holding a pointer type.
 */
static void verifier_mark_reg_known_zero(struct bpf_reg_state *reg)
{
    verifier_mark_reg_known(reg, 0);
}

static void verifier_mark_reg_const_zero(struct bpf_reg_state *reg)
{
    verifier_mark_reg_known(reg, 0);
    reg->type = SCALAR_VALUE;
}

static void mark_reg_known_zero(struct bpf_verifier_env *env, struct bpf_reg_state *regs, u32 regno)
{
    if (WARN_ON(regno >= MAX_BPF_REG)) {
        verbose(env, "mark_reg_known_zero(regs, %u)\n", regno);
        /* Something bad happened, let's kill all regs */
        for (regno = 0; regno < MAX_BPF_REG; regno++) {
            verifier_mark_reg_not_init(env, regs + regno);
        }
        return;
    }
    verifier_mark_reg_known_zero(regs + regno);
}

static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg)
{
    return type_is_pkt_pointer(reg->type);
}

static bool reg_is_pkt_pointer_any(const struct bpf_reg_state *reg)
{
    return reg_is_pkt_pointer(reg) || reg->type == PTR_TO_PACKET_END;
}

/* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */
static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg, enum bpf_reg_type which)
{
    /* The register can already have a range from prior markings.
     * This is fine as long as it hasn't been advanced from its
     * origin.
     */
    return reg->type == which && reg->id == 0 && reg->off == 0 && tnum_equals_const(reg->var_off, 0);
}

/* Reset the min/max bounds of a register */
static void verifier_mark_reg_unbounded(struct bpf_reg_state *reg)
{
    reg->smin_value = S64_MIN;
    reg->smax_value = S64_MAX;
    reg->umin_value = 0;
    reg->umax_value = U64_MAX;

    reg->s32_min_value = S32_MIN;
    reg->s32_max_value = S32_MAX;
    reg->u32_min_value = 0;
    reg->u32_max_value = U32_MAX;
}

static void verifier_mark_reg64_unbounded(struct bpf_reg_state *reg)
{
    reg->smin_value = S64_MIN;
    reg->smax_value = S64_MAX;
    reg->umin_value = 0;
    reg->umax_value = U64_MAX;
}

static void verifier_mark_reg32_unbounded(struct bpf_reg_state *reg)
{
    reg->s32_min_value = S32_MIN;
    reg->s32_max_value = S32_MAX;
    reg->u32_min_value = 0;
    reg->u32_max_value = U32_MAX;
}

static void verifier_update_reg32_bounds(struct bpf_reg_state *reg)
{
    struct tnum var32_off = tnum_subreg(reg->var_off);

    /* min signed is max(sign bit) | min(other bits) */
    reg->s32_min_value = max_t(s32, reg->s32_min_value, var32_off.value | (var32_off.mask & S32_MIN));
    /* max signed is min(sign bit) | max(other bits) */
    reg->s32_max_value = min_t(s32, reg->s32_max_value, var32_off.value | (var32_off.mask & S32_MAX));
    reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)var32_off.value);
    reg->u32_max_value = min(reg->u32_max_value, (u32)(var32_off.value | var32_off.mask));
}

static void verifier_update_reg64_bounds(struct bpf_reg_state *reg)
{
    /* min signed is max(sign bit) | min(other bits) */
    reg->smin_value = max_t(s64, reg->smin_value, reg->var_off.value | (reg->var_off.mask & S64_MIN));
    /* max signed is min(sign bit) | max(other bits) */
    reg->smax_value = min_t(s64, reg->smax_value, reg->var_off.value | (reg->var_off.mask & S64_MAX));
    reg->umin_value = max(reg->umin_value, reg->var_off.value);
    reg->umax_value = min(reg->umax_value, reg->var_off.value | reg->var_off.mask);
}

static void verifier_update_reg_bounds(struct bpf_reg_state *reg)
{
    verifier_update_reg32_bounds(reg);
    verifier_update_reg64_bounds(reg);
}

/* Uses signed min/max values to inform unsigned, and vice-versa */
static void verifier_reg32_deduce_bounds(struct bpf_reg_state *reg)
{
    /* Learn sign from signed bounds.
     * If we cannot cross the sign boundary, then signed and unsigned bounds
     * are the same, so combine.  This works even in the negative case, e.g.
     * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
     */
    if (reg->s32_min_value >= 0 || reg->s32_max_value < 0) {
        reg->s32_min_value = reg->u32_min_value = max_t(u32, reg->s32_min_value, reg->u32_min_value);
        reg->s32_max_value = reg->u32_max_value = min_t(u32, reg->s32_max_value, reg->u32_max_value);
        return;
    }
    /* Learn sign from unsigned bounds.  Signed bounds cross the sign
     * boundary, so we must be careful.
     */
    if ((s32)reg->u32_max_value >= 0) {
        /* Positive.  We can't learn anything from the smin, but smax
         * is positive, hence safe.
         */
        reg->s32_min_value = reg->u32_min_value;
        reg->s32_max_value = reg->u32_max_value = min_t(u32, reg->s32_max_value, reg->u32_max_value);
    } else if ((s32)reg->u32_min_value < 0) {
        /* Negative.  We can't learn anything from the smax, but smin
         * is negative, hence safe.
         */
        reg->s32_min_value = reg->u32_min_value = max_t(u32, reg->s32_min_value, reg->u32_min_value);
        reg->s32_max_value = reg->u32_max_value;
    }
}

static void verifier_reg64_deduce_bounds(struct bpf_reg_state *reg)
{
    /* Learn sign from signed bounds.
     * If we cannot cross the sign boundary, then signed and unsigned bounds
     * are the same, so combine.  This works even in the negative case, e.g.
     * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
     */
    if (reg->smin_value >= 0 || reg->smax_value < 0) {
        reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value, reg->umin_value);
        reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value, reg->umax_value);
        return;
    }
    /* Learn sign from unsigned bounds.  Signed bounds cross the sign
     * boundary, so we must be careful.
     */
    if ((s64)reg->umax_value >= 0) {
        /* Positive.  We can't learn anything from the smin, but smax
         * is positive, hence safe.
         */
        reg->smin_value = reg->umin_value;
        reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value, reg->umax_value);
    } else if ((s64)reg->umin_value < 0) {
        /* Negative.  We can't learn anything from the smax, but smin
         * is negative, hence safe.
         */
        reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value, reg->umin_value);
        reg->smax_value = reg->umax_value;
    }
}

static void verifier_reg_deduce_bounds(struct bpf_reg_state *reg)
{
    verifier_reg32_deduce_bounds(reg);
    verifier_reg64_deduce_bounds(reg);
}

/* Attempts to improve var_off based on unsigned min/max information */
static void verifier_reg_bound_offset(struct bpf_reg_state *reg)
{
    struct tnum var64_off = tnum_intersect(reg->var_off, tnum_range(reg->umin_value, reg->umax_value));
    struct tnum var32_off =
        tnum_intersect(tnum_subreg(reg->var_off), tnum_range(reg->u32_min_value, reg->u32_max_value));

    reg->var_off = tnum_or(tnum_clear_subreg(var64_off), var32_off);
}

static void reg_bounds_sync(struct bpf_reg_state *reg)
{
    /* We might have learned new bounds from the var_off. */
    verifier_update_reg_bounds(reg);
    /* We might have learned something about the sign bit. */
    verifier_reg_deduce_bounds(reg);
    /* We might have learned some bits from the bounds. */
    verifier_reg_bound_offset(reg);
    /* Intersecting with the old var_off might have improved our bounds
     * slightly, e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
     * then new var_off is (0; 0x7f...fc) which improves our umax.
     */
    verifier_update_reg_bounds(reg);
}
static bool verifier_reg32_bound_s64(s32 a)
{
    return a >= 0 && a <= S32_MAX;
}

static void verifier_reg_assign_32_into_64(struct bpf_reg_state *reg)
{
    reg->umin_value = reg->u32_min_value;
    reg->umax_value = reg->u32_max_value;

    /* Attempt to pull 32-bit signed bounds into 64-bit bounds but must
     * be positive otherwise set to worse case bounds and refine later
     * from tnum.
     */
    if (verifier_reg32_bound_s64(reg->s32_min_value) && verifier_reg32_bound_s64(reg->s32_max_value)) {
        reg->smin_value = reg->s32_min_value;
        reg->smax_value = reg->s32_max_value;
    } else {
        reg->smin_value = 0;
        reg->smax_value = U32_MAX;
    }
}

static void verifier_reg_combine_32_into_64(struct bpf_reg_state *reg)
{
    /* special case when 64-bit register has upper 32-bit register
     * zeroed. Typically happens after zext or <<32, >>32 sequence
     * allowing us to use 32-bit bounds directly,
     */
    if (tnum_equals_const(tnum_clear_subreg(reg->var_off), 0)) {
        verifier_reg_assign_32_into_64(reg);
    } else {
        /* Otherwise the best we can do is push lower 32bit known and
         * unknown bits into register (var_off set from jmp logic)
         * then learn as much as possible from the 64-bit tnum
         * known and unknown bits. The previous smin/smax bounds are
         * invalid here because of jmp32 compare so mark them unknown
         * so they do not impact tnum bounds calculation.
         */
        verifier_mark_reg64_unbounded(reg);
        verifier_update_reg_bounds(reg);
    }

    /* Intersecting with the old var_off might have improved our bounds
     * slightly.  e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
     * then new var_off is (0; 0x7f...fc) which improves our umax.
     */
    reg_bounds_sync(reg);
}

static bool verifier_reg64_bound_s32(s64 a)
{
    return a > S32_MIN && a < S32_MAX;
}

static bool verifier_reg64_bound_u32(u64 a)
{
    return a > U32_MIN && a < U32_MAX;
}

static void __reg_combine_64_into_32(struct bpf_reg_state *reg)
{
    verifier_mark_reg32_unbounded(reg);

    if (verifier_reg64_bound_s32(reg->smin_value) && verifier_reg64_bound_s32(reg->smax_value)) {
        reg->s32_min_value = (s32)reg->smin_value;
        reg->s32_max_value = (s32)reg->smax_value;
    }
    if (verifier_reg64_bound_u32(reg->umin_value) && verifier_reg64_bound_u32(reg->umax_value)) {
        reg->u32_min_value = (u32)reg->umin_value;
        reg->u32_max_value = (u32)reg->umax_value;
    }

    /* Intersecting with the old var_off might have improved our bounds
     * slightly.  e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
     * then new var_off is (0; 0x7f...fc) which improves our umax.
     */
    reg_bounds_sync(reg);
}

/* Mark a register as having a completely unknown (scalar) value. */
static void __mark_reg_unknown(const struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
    /*
     * Clear type, id, off, and union(map_ptr, range) and
     * padding between 'type' and union
     */
    memset(reg, 0, offsetof(struct bpf_reg_state, var_off));
    reg->type = SCALAR_VALUE;
    reg->var_off = tnum_unknown;
    reg->frameno = 0;
    reg->precise = env->subprog_cnt > 1 || !env->bpf_capable;
    verifier_mark_reg_unbounded(reg);
}

static void mark_reg_unknown(struct bpf_verifier_env *env, struct bpf_reg_state *regs, u32 regno)
{
    if (WARN_ON(regno >= MAX_BPF_REG)) {
        verbose(env, "mark_reg_unknown(regs, %u)\n", regno);
        /* Something bad happened, let's kill all regs except FP */
        for (regno = 0; regno < BPF_REG_FP; regno++) {
            verifier_mark_reg_not_init(env, regs + regno);
        }
        return;
    }
    __mark_reg_unknown(env, regs + regno);
}

static void verifier_mark_reg_not_init(const struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
    __mark_reg_unknown(env, reg);
    reg->type = NOT_INIT;
}

static void mark_reg_not_init(struct bpf_verifier_env *env, struct bpf_reg_state *regs, u32 regno)
{
    if (WARN_ON(regno >= MAX_BPF_REG)) {
        verbose(env, "mark_reg_not_init(regs, %u)\n", regno);
        /* Something bad happened, let's kill all regs except FP */
        for (regno = 0; regno < BPF_REG_FP; regno++) {
            verifier_mark_reg_not_init(env, regs + regno);
        }
        return;
    }
    verifier_mark_reg_not_init(env, regs + regno);
}

static void mark_btf_ld_reg(struct bpf_verifier_env *env, struct bpf_reg_state *regs, u32 regno,
                            enum bpf_reg_type reg_type, u32 btf_id)
{
    if (reg_type == SCALAR_VALUE) {
        mark_reg_unknown(env, regs, regno);
        return;
    }
    mark_reg_known_zero(env, regs, regno);
    regs[regno].type = PTR_TO_BTF_ID;
    regs[regno].btf_id = btf_id;
}

#define DEF_NOT_SUBREG (0)
static void init_reg_state(struct bpf_verifier_env *env, struct bpf_func_state *state)
{
    struct bpf_reg_state *regs = state->regs;
    int i;

    for (i = 0; i < MAX_BPF_REG; i++) {
        mark_reg_not_init(env, regs, i);
        regs[i].live = REG_LIVE_NONE;
        regs[i].parent = NULL;
        regs[i].subreg_def = DEF_NOT_SUBREG;
    }

    /* frame pointer */
    regs[BPF_REG_FP].type = PTR_TO_STACK;
    mark_reg_known_zero(env, regs, BPF_REG_FP);
    regs[BPF_REG_FP].frameno = state->frameno;
}

#define BPF_MAIN_FUNC (-1)
static void init_func_state(struct bpf_verifier_env *env, struct bpf_func_state *state, int callsite, int frameno,
                            int subprogno)
{
    state->callsite = callsite;
    state->frameno = frameno;
    state->subprogno = subprogno;
    init_reg_state(env, state);
}

enum reg_arg_type {
    SRC_OP,        /* register is used as source operand */
    DST_OP,        /* register is used as destination operand */
    DST_OP_NO_MARK /* same as above, check only, don't mark */
};

static int cmp_subprogs(const void *a, const void *b)
{
    return ((struct bpf_subprog_info *)a)->start - ((struct bpf_subprog_info *)b)->start;
}

static int find_subprog(struct bpf_verifier_env *env, int off)
{
    struct bpf_subprog_info *p;

    p = bsearch(&off, env->subprog_info, env->subprog_cnt, sizeof(env->subprog_info[0]), cmp_subprogs);
    if (!p) {
        return -ENOENT;
    }
    return p - env->subprog_info;
}

static int add_subprog(struct bpf_verifier_env *env, int off)
{
    int insn_cnt = env->prog->len;
    int ret;

    if (off >= insn_cnt || off < 0) {
        verbose(env, "call to invalid destination\n");
        return -EINVAL;
    }
    ret = find_subprog(env, off);
    if (ret >= 0) {
        return 0;
    }
    if (env->subprog_cnt >= BPF_MAX_SUBPROGS) {
        verbose(env, "too many subprograms\n");
        return -E2BIG;
    }
    env->subprog_info[env->subprog_cnt++].start = off;
    sort(env->subprog_info, env->subprog_cnt, sizeof(env->subprog_info[0]), cmp_subprogs, NULL);
    return 0;
}

static int check_subprogs(struct bpf_verifier_env *env)
{
    int i, ret, subprog_start, subprog_end, off, cur_subprog = 0;
    struct bpf_subprog_info *subprog = env->subprog_info;
    struct bpf_insn *insn = env->prog->insnsi;
    int insn_cnt = env->prog->len;

    /* Add entry function. */
    ret = add_subprog(env, 0);
    if (ret < 0) {
        return ret;
    }

    /* determine subprog starts. The end is one before the next starts */
    for (i = 0; i < insn_cnt; i++) {
        if (insn[i].code != (BPF_JMP | BPF_CALL)) {
            continue;
        }
        if (insn[i].src_reg != BPF_PSEUDO_CALL) {
            continue;
        }
        if (!env->bpf_capable) {
            verbose(env, "function calls to other bpf functions are allowed for CAP_BPF and CAP_SYS_ADMIN\n");
            return -EPERM;
        }
        ret = add_subprog(env, i + insn[i].imm + 1);
        if (ret < 0) {
            return ret;
        }
    }

    /* Add a fake 'exit' subprog which could simplify subprog iteration
     * logic. 'subprog_cnt' should not be increased.
     */
    subprog[env->subprog_cnt].start = insn_cnt;

    if (env->log.level & BPF_LOG_LEVEL2) {
        for (i = 0; i < env->subprog_cnt; i++) {
            verbose(env, "func#%d @%d\n", i, subprog[i].start);
        }
    }

    /* now check that all jumps are within the same subprog */
    subprog_start = subprog[cur_subprog].start;
    subprog_end = subprog[cur_subprog + 1].start;
    for (i = 0; i < insn_cnt; i++) {
        u8 code = insn[i].code;

        if (code == (BPF_JMP | BPF_CALL) && insn[i].imm == BPF_FUNC_tail_call && insn[i].src_reg != BPF_PSEUDO_CALL) {
            subprog[cur_subprog].has_tail_call = true;
        }
        if (BPF_CLASS(code) == BPF_LD && (BPF_MODE(code) == BPF_ABS || BPF_MODE(code) == BPF_IND)) {
            subprog[cur_subprog].has_ld_abs = true;
        }
        if (BPF_CLASS(code) != BPF_JMP && BPF_CLASS(code) != BPF_JMP32) {
            goto next;
        }
        if (BPF_OP(code) == BPF_EXIT || BPF_OP(code) == BPF_CALL) {
            goto next;
        }
        off = i + insn[i].off + 1;
        if (off < subprog_start || off >= subprog_end) {
            verbose(env, "jump out of range from insn %d to %d\n", i, off);
            return -EINVAL;
        }
    next:
        if (i == subprog_end - 1) {
            /* to avoid fall-through from one subprog into another
             * the last insn of the subprog should be either exit
             * or unconditional jump back
             */
            if (code != (BPF_JMP | BPF_EXIT) && code != (BPF_JMP | BPF_JA)) {
                verbose(env, "last insn is not an exit or jmp\n");
                return -EINVAL;
            }
            subprog_start = subprog_end;
            cur_subprog++;
            if (cur_subprog < env->subprog_cnt) {
                subprog_end = subprog[cur_subprog + 1].start;
            }
        }
    }
    return 0;
}

/* Parentage chain of this register (or stack slot) should take care of all
 * issues like callee-saved registers, stack slot allocation time, etc.
 */
static int mark_reg_read(struct bpf_verifier_env *env, const struct bpf_reg_state *state, struct bpf_reg_state *parent,
                         u8 flag)
{
    bool writes = parent == state->parent; /* Observe write marks */
    int cnt = 0;

    while (parent) {
        /* if read wasn't screened by an earlier write ... */
        if (writes && (state->live & REG_LIVE_WRITTEN)) {
            break;
        }
        if (parent->live & REG_LIVE_DONE) {
            verbose(env, "verifier BUG type %s var_off %lld off %d\n", reg_type_str(env, parent->type),
                    parent->var_off.value, parent->off);
            return -EFAULT;
        }
        /* The first condition is more likely to be true than the
         * second, checked it first.
         */
        if ((parent->live & REG_LIVE_READ) == flag || (parent->live & REG_LIVE_READ64)) {
            /* The parentage chain never changes and
             * this parent was already marked as LIVE_READ.
             * There is no need to keep walking the chain again and
             * keep re-marking all parents as LIVE_READ.
             * This case happens when the same register is read
             * multiple times without writes into it in-between.
             * Also, if parent has the stronger REG_LIVE_READ64 set,
             * then no need to set the weak REG_LIVE_READ32.
             */
            break;
        }
        /* ... then we depend on parent's value */
        parent->live |= flag;
        /* REG_LIVE_READ64 overrides REG_LIVE_READ32. */
        if (flag == REG_LIVE_READ64) {
            parent->live &= ~REG_LIVE_READ32;
        }
        state = parent;
        parent = state->parent;
        writes = true;
        cnt++;
    }

    if (env->longest_mark_read_walk < cnt) {
        env->longest_mark_read_walk = cnt;
    }
    return 0;
}

/* This function is supposed to be used by the following 32-bit optimization
 * code only. It returns TRUE if the source or destination register operates
 * on 64-bit, otherwise return FALSE.
 */
static bool is_reg64(struct bpf_verifier_env *env, struct bpf_insn *insn, u32 regno, struct bpf_reg_state *reg,
                     enum reg_arg_type t)
{
    u8 code, class, op;

    code = insn->code;
    class = BPF_CLASS(code);
    op = BPF_OP(code);
    if (class == BPF_JMP) {
        /* BPF_EXIT for "main" will reach here. Return TRUE
         * conservatively.
         */
        if (op == BPF_EXIT) {
            return true;
        }
        if (op == BPF_CALL) {
            /* BPF to BPF call will reach here because of marking
             * caller saved clobber with DST_OP_NO_MARK for which we
             * don't care the register def because they are anyway
             * marked as NOT_INIT already.
             */
            if (insn->src_reg == BPF_PSEUDO_CALL) {
                return false;
            }
            /* Helper call will reach here because of arg type
             * check, conservatively return TRUE.
             */
            if (t == SRC_OP) {
                return true;
            }

            return false;
        }
    }

    if (class == BPF_ALU64 || class == BPF_JMP ||
        /* BPF_END always use BPF_ALU class. */
        (class == BPF_ALU && op == BPF_END && insn->imm == VERIFIER_SIXTYFOUR)) {
        return true;
    }

    if (class == BPF_ALU || class == BPF_JMP32) {
        return false;
    }

    if (class == BPF_LDX) {
        if (t != SRC_OP) {
            return BPF_SIZE(code) == BPF_DW;
        }
        /* LDX source must be ptr. */
        return true;
    }

    if (class == BPF_STX) {
        if (reg->type != SCALAR_VALUE) {
            return true;
        }
        return BPF_SIZE(code) == BPF_DW;
    }

    if (class == BPF_LD) {
        u8 mode = BPF_MODE(code);
        /* LD_IMM64 */
        if (mode == BPF_IMM) {
            return true;
        }

        /* Both LD_IND and LD_ABS return 32-bit data. */
        if (t != SRC_OP) {
            return false;
        }

        /* Implicit ctx ptr. */
        if (regno == BPF_REG_6) {
            return true;
        }

        /* Explicit source could be any width. */
        return true;
    }

    if (class == BPF_ST) {
        /* The only source register for BPF_ST is a ptr. */
        return true;
    }

    /* Conservatively return true at default. */
    return true;
}

/* Return TRUE if INSN doesn't have explicit value define. */
static bool insn_no_def(struct bpf_insn *insn)
{
    u8 class = BPF_CLASS(insn->code);

    return (class == BPF_JMP || class == BPF_JMP32 || class == BPF_STX || class == BPF_ST);
}

/* Return TRUE if INSN has defined any 32-bit value explicitly. */
static bool insn_has_def32(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
    if (insn_no_def(insn)) {
        return false;
    }

    return !is_reg64(env, insn, insn->dst_reg, NULL, DST_OP);
}

static void mark_insn_zext(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
    s32 def_idx = reg->subreg_def;

    if (def_idx == DEF_NOT_SUBREG) {
        return;
    }

    env->insn_aux_data[def_idx - 1].zext_dst = true;
    /* The dst will be zero extended, so won't be sub-register anymore. */
    reg->subreg_def = DEF_NOT_SUBREG;
}

static int check_reg_arg(struct bpf_verifier_env *env, u32 regno, enum reg_arg_type t)
{
    struct bpf_verifier_state *vstate = env->cur_state;
    struct bpf_func_state *state = vstate->frame[vstate->curframe];
    struct bpf_insn *insn = env->prog->insnsi + env->insn_idx;
    struct bpf_reg_state *reg, *regs = state->regs;
    bool rw64;

    if (regno >= MAX_BPF_REG) {
        verbose(env, "R%d is invalid\n", regno);
        return -EINVAL;
    }

    reg = &regs[regno];
    rw64 = is_reg64(env, insn, regno, reg, t);
    if (t == SRC_OP) {
        /* check whether register used as source operand can be read */
        if (reg->type == NOT_INIT) {
            verbose(env, "R%d !read_ok\n", regno);
            return -EACCES;
        }
        /* We don't need to worry about FP liveness because it's read-only */
        if (regno == BPF_REG_FP) {
            return 0;
        }

        if (rw64) {
            mark_insn_zext(env, reg);
        }

        return mark_reg_read(env, reg, reg->parent, rw64 ? REG_LIVE_READ64 : REG_LIVE_READ32);
    } else {
        /* check whether register used as dest operand can be written to */
        if (regno == BPF_REG_FP) {
            verbose(env, "frame pointer is read only\n");
            return -EACCES;
        }
        reg->live |= REG_LIVE_WRITTEN;
        reg->subreg_def = rw64 ? DEF_NOT_SUBREG : env->insn_idx + 1;
        if (t == DST_OP) {
            mark_reg_unknown(env, regs, regno);
        }
    }
    return 0;
}

/* for any branch, call, exit record the history of jmps in the given state */
static int push_jmp_history(struct bpf_verifier_env *env, struct bpf_verifier_state *cur)
{
    u32 cnt = cur->jmp_history_cnt;
    struct bpf_idx_pair *p;

    cnt++;
    p = krealloc(cur->jmp_history, cnt * sizeof(*p), GFP_USER);
    if (!p) {
        return -ENOMEM;
    }
    p[cnt - 1].idx = env->insn_idx;
    p[cnt - 1].prev_idx = env->prev_insn_idx;
    cur->jmp_history = p;
    cur->jmp_history_cnt = cnt;
    return 0;
}

/* Backtrack one insn at a time. If idx is not at the top of recorded
 * history then previous instruction came from straight line execution.
 */
static int get_prev_insn_idx(struct bpf_verifier_state *st, int i, u32 *history)
{
    u32 cnt = *history;

    if (cnt && st->jmp_history[cnt - 1].idx == i) {
        i = st->jmp_history[cnt - 1].prev_idx;
        (*history)--;
    } else {
        i--;
    }
    return i;
}

/* For given verifier state backtrack_insn() is called from the last insn to
 * the first insn. Its purpose is to compute a bitmask of registers and
 * stack slots that needs precision in the parent verifier state.
 */
static int backtrack_insn(struct bpf_verifier_env *env, int idx, u32 *reg_mask, u64 *stack_mask)
{
    const struct bpf_insn_cbs cbs = {
        .cb_print = verbose,
        .private_data = env,
    };
    struct bpf_insn *insn = env->prog->insnsi + idx;
    u8 class = BPF_CLASS(insn->code);
    u8 opcode = BPF_OP(insn->code);
    u8 mode = BPF_MODE(insn->code);
    u32 dreg = 1u << insn->dst_reg;
    u32 sreg = 1u << insn->src_reg;
    u32 spi;

    if (insn->code == 0) {
        return 0;
    }
    if (env->log.level & BPF_LOG_LEVEL) {
        verbose(env, "regs=%x stack=%llx before ", *reg_mask, *stack_mask);
        verbose(env, "%d: ", idx);
        print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
    }

    if (class == BPF_ALU || class == BPF_ALU64) {
        if (!(*reg_mask & dreg)) {
            return 0;
        }
        if (opcode == BPF_MOV) {
            if (BPF_SRC(insn->code) == BPF_X) {
                /* dreg = sreg
                 * dreg needs precision after this insn
                 * sreg needs precision before this insn
                 */
                *reg_mask &= ~dreg;
                *reg_mask |= sreg;
            } else {
                /* dreg = K
                 * dreg needs precision after this insn.
                 * Corresponding register is already marked
                 * as precise=true in this verifier state.
                 * No further markings in parent are necessary
                 */
                *reg_mask &= ~dreg;
            }
        } else {
            if (BPF_SRC(insn->code) == BPF_X) {
                /* dreg += sreg
                 * both dreg and sreg need precision
                 * before this insn
                 */
                *reg_mask |= sreg;
            }
            /* else dreg += K
             * dreg still needs precision before this insn
             */
        }
    } else if (class == BPF_LDX) {
        if (!(*reg_mask & dreg)) {
            return 0;
        }
        *reg_mask &= ~dreg;

        /* scalars can only be spilled into stack w/o losing precision.
         * Load from any other memory can be zero extended.
         * The desire to keep that precision is already indicated
         * by 'precise' mark in corresponding register of this state.
         * No further tracking necessary.
         */
        if (insn->src_reg != BPF_REG_FP) {
            return 0;
        }
        if (BPF_SIZE(insn->code) != BPF_DW) {
            return 0;
        }

        /* dreg = *(u64 *)[fp - off] was a fill from the stack.
         * that [fp - off] slot contains scalar that needs to be
         * tracked with precision
         */
        spi = (-insn->off - 1) / BPF_REG_SIZE;
        if (spi >= VERIFIER_SIXTYFOUR) {
            verbose(env, "BUG spi %d\n", spi);
            WARN_ONCE(1, "verifier backtracking bug");
            return -EFAULT;
        }
        *stack_mask |= 1ull << spi;
    } else if (class == BPF_STX || class == BPF_ST) {
        if (*reg_mask & dreg) {
            /* stx & st shouldn't be using _scalar_ dst_reg
             * to access memory. It means backtracking
             * encountered a case of pointer subtraction.
             */
            return -ENOTSUPP;
        }
        /* scalars can only be spilled into stack */
        if (insn->dst_reg != BPF_REG_FP) {
            return 0;
        }
        if (BPF_SIZE(insn->code) != BPF_DW) {
            return 0;
        }
        spi = (-insn->off - 1) / BPF_REG_SIZE;
        if (spi >= VERIFIER_SIXTYFOUR) {
            verbose(env, "BUG spi %d\n", spi);
            WARN_ONCE(1, "verifier backtracking bug");
            return -EFAULT;
        }
        if (!(*stack_mask & (1ull << spi))) {
            return 0;
        }
        *stack_mask &= ~(1ull << spi);
        if (class == BPF_STX) {
            *reg_mask |= sreg;
        }
    } else if (class == BPF_JMP || class == BPF_JMP32) {
        if (opcode == BPF_CALL) {
            if (insn->src_reg == BPF_PSEUDO_CALL) {
                return -ENOTSUPP;
            }
            /* regular helper call sets R0 */
            *reg_mask &= ~1;
            if (*reg_mask & 0x3f) {
                /* if backtracing was looking for registers R1-R5
                 * they should have been found already.
                 */
                verbose(env, "BUG regs %x\n", *reg_mask);
                WARN_ONCE(1, "verifier backtracking bug");
                return -EFAULT;
            }
        } else if (opcode == BPF_EXIT) {
            return -ENOTSUPP;
        }
    } else if (class == BPF_LD) {
        if (!(*reg_mask & dreg)) {
            return 0;
        }
        *reg_mask &= ~dreg;
        /* It's ld_imm64 or ld_abs or ld_ind.
         * For ld_imm64 no further tracking of precision
         * into parent is necessary
         */
        if (mode == BPF_IND || mode == BPF_ABS) {
            /* to be analyzed */
            return -ENOTSUPP;
        }
    }
    return 0;
}

/* the scalar precision tracking algorithm:
 * . at the start all registers have precise=false.
 * . scalar ranges are tracked as normal through alu and jmp insns.
 * . once precise value of the scalar register is used in:
 *   .  ptr + scalar alu
 *   . if (scalar cond K|scalar)
 *   .  helper_call(.., scalar, ...) where ARG_CONST is expected
 *   backtrack through the verifier states and mark all registers and
 *   stack slots with spilled constants that these scalar regisers
 *   should be precise.
 * . during state pruning two registers (or spilled stack slots)
 *   are equivalent if both are not precise.
 *
 * Note the verifier cannot simply walk register parentage chain,
 * since many different registers and stack slots could have been
 * used to compute single precise scalar.
 *
 * The approach of starting with precise=true for all registers and then
 * backtrack to mark a register as not precise when the verifier detects
 * that program doesn't care about specific value (e.g., when helper
 * takes register as ARG_ANYTHING parameter) is not safe.
 *
 * It's ok to walk single parentage chain of the verifier states.
 * It's possible that this backtracking will go all the way till 1st insn.
 * All other branches will be explored for needing precision later.
 *
 * The backtracking needs to deal with cases like:
 *   R8=map_value(id=0,off=0,ks=4,vs=1952,imm=0) R9_w=map_value(id=0,off=40,ks=4,vs=1952,imm=0)
 * r9 -= r8
 * r5 = r9
 * if r5 > 0x79f goto pc+7
 *    R5_w=inv(id=0,umax_value=1951,var_off=(0x0; 0x7ff))
 * r5 += 1
 * ...
 * call bpf_perf_event_output#25
 *   where .arg5_type = ARG_CONST_SIZE_OR_ZERO
 *
 * and this case:
 * r6 = 1
 * call foo // uses callee's r6 inside to compute r0
 * r0 += r6
 * if r0 == 0 goto
 *
 * to track above reg_mask/stack_mask needs to be independent for each frame.
 *
 * Also if parent's curframe > frame where backtracking started,
 * the verifier need to mark registers in both frames, otherwise callees
 * may incorrectly prune callers. This is similar to
 * commit 7640ead93924 ("bpf: verifier: make sure callees don't prune with caller differences")
 *
 * For now backtracking falls back into conservative marking.
 */
static void mark_all_scalars_precise(struct bpf_verifier_env *env, struct bpf_verifier_state *st)
{
    struct bpf_func_state *func;
    struct bpf_reg_state *reg;
    int i, j;

    /* big hammer: mark all scalars precise in this path.
     * pop_stack may still get !precise scalars.
     */
    for (; st; st = st->parent) {
        for (i = 0; i <= st->curframe; i++) {
            func = st->frame[i];
            for (j = 0; j < BPF_REG_FP; j++) {
                reg = &func->regs[j];
                if (reg->type != SCALAR_VALUE) {
                    continue;
                }
                reg->precise = true;
            }
            for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) {
                if (func->stack[j].slot_type[0] != STACK_SPILL) {
                    continue;
                }
                reg = &func->stack[j].spilled_ptr;
                if (reg->type != SCALAR_VALUE) {
                    continue;
                }
                reg->precise = true;
            }
        }
    }
}

static int __mark_chain_precision(struct bpf_verifier_env *env, int regno, int spi)
{
    struct bpf_verifier_state *st = env->cur_state;
    int first_idx = st->first_insn_idx;
    int last_idx = env->insn_idx;
    struct bpf_func_state *func;
    struct bpf_reg_state *reg;
    u32 reg_mask = regno >= 0 ? 1u << regno : 0;
    u64 stack_mask = spi >= 0 ? 1ull << spi : 0;
    bool skip_first = true;
    bool new_marks = false;
    int i, err;

    if (!env->bpf_capable) {
        return 0;
    }

    func = st->frame[st->curframe];
    if (regno >= 0) {
        reg = &func->regs[regno];
        if (reg->type != SCALAR_VALUE) {
            WARN_ONCE(1, "backtracing misuse");
            return -EFAULT;
        }
        if (!reg->precise) {
            new_marks = true;
        } else {
            reg_mask = 0;
        }
        reg->precise = true;
    }

    while (spi >= 0) {
        if (func->stack[spi].slot_type[0] != STACK_SPILL) {
            stack_mask = 0;
            break;
        }
        reg = &func->stack[spi].spilled_ptr;
        if (reg->type != SCALAR_VALUE) {
            stack_mask = 0;
            break;
        }
        if (!reg->precise) {
            new_marks = true;
        } else {
            stack_mask = 0;
        }
        reg->precise = true;
        break;
    }

    if (!new_marks) {
        return 0;
    }
    if (!reg_mask && !stack_mask) {
        return 0;
    }
    for (;;) {
        DECLARE_BITMAP(mask, VERIFIER_SIXTYFOUR);
        u32 history = st->jmp_history_cnt;

        if (env->log.level & BPF_LOG_LEVEL) {
            verbose(env, "last_idx %d first_idx %d\n", last_idx, first_idx);
        }
        for (i = last_idx;;) {
            if (skip_first) {
                err = 0;
                skip_first = false;
            } else {
                err = backtrack_insn(env, i, &reg_mask, &stack_mask);
            }
            if (err == -ENOTSUPP) {
                mark_all_scalars_precise(env, st);
                return 0;
            } else if (err) {
                return err;
            }
            if (!reg_mask && !stack_mask) {
                /* Found assignment(s) into tracked register in this state.
                 * Since this state is already marked, just return.
                 * Nothing to be tracked further in the parent state.
                 */
                return 0;
            }
            if (i == first_idx) {
                break;
            }
            i = get_prev_insn_idx(st, i, &history);
            if (i >= env->prog->len) {
                /* This can happen if backtracking reached insn 0
                 * and there are still reg_mask or stack_mask
                 * to backtrack.
                 * It means the backtracking missed the spot where
                 * particular register was initialized with a constant.
                 */
                verbose(env, "BUG backtracking idx %d\n", i);
                WARN_ONCE(1, "verifier backtracking bug");
                return -EFAULT;
            }
        }
        st = st->parent;
        if (!st) {
            break;
        }

        new_marks = false;
        func = st->frame[st->curframe];
        bitmap_from_u64(mask, reg_mask);
        for_each_set_bit(i, mask, 0x20)
        {
            reg = &func->regs[i];
            if (reg->type != SCALAR_VALUE) {
                reg_mask &= ~(1u << i);
                continue;
            }
            if (!reg->precise) {
                new_marks = true;
            }
            reg->precise = true;
        }

        bitmap_from_u64(mask, stack_mask);
        for_each_set_bit(i, mask, VERIFIER_SIXTYFOUR)
        {
            if (i >= func->allocated_stack / BPF_REG_SIZE) {
                /* the sequence of instructions:
                 * 2: (bf) r3 = r10
                 * 3: (7b) *(u64 *)(r3 -8) = r0
                 * 4: (79) r4 = *(u64 *)(r10 -8)
                 * doesn't contain jmps. It's backtracked
                 * as a single block.
                 * During backtracking insn 3 is not recognized as
                 * stack access, so at the end of backtracking
                 * stack slot fp-8 is still marked in stack_mask.
                 * However the parent state may not have accessed
                 * fp-8 and it's "unallocated" stack space.
                 * In such case fallback to conservative.
                 */
                mark_all_scalars_precise(env, st);
                return 0;
            }

            if (func->stack[i].slot_type[0] != STACK_SPILL) {
                stack_mask &= ~(1ull << i);
                continue;
            }
            reg = &func->stack[i].spilled_ptr;
            if (reg->type != SCALAR_VALUE) {
                stack_mask &= ~(1ull << i);
                continue;
            }
            if (!reg->precise) {
                new_marks = true;
            }
            reg->precise = true;
        }
        if (env->log.level & BPF_LOG_LEVEL) {
            print_verifier_state(env, func);
            verbose(env, "parent %s regs=%x stack=%llx marks\n", new_marks ? "didn't have" : "already had", reg_mask,
                    stack_mask);
        }

        if (!reg_mask && !stack_mask) {
            break;
        }
        if (!new_marks) {
            break;
        }

        last_idx = st->last_insn_idx;
        first_idx = st->first_insn_idx;
    }
    return 0;
}

static int mark_chain_precision(struct bpf_verifier_env *env, int regno)
{
    return __mark_chain_precision(env, regno, -1);
}

static int mark_chain_precision_stack(struct bpf_verifier_env *env, int spi)
{
    return __mark_chain_precision(env, -1, spi);
}

static bool is_spillable_regtype(enum bpf_reg_type type)
{
    switch (base_type(type)) {
        case PTR_TO_MAP_VALUE:
        case PTR_TO_STACK:
        case PTR_TO_CTX:
        case PTR_TO_PACKET:
        case PTR_TO_PACKET_META:
        case PTR_TO_PACKET_END:
        case PTR_TO_FLOW_KEYS:
        case CONST_PTR_TO_MAP:
        case PTR_TO_SOCKET:
        case PTR_TO_SOCK_COMMON:
        case PTR_TO_TCP_SOCK:
        case PTR_TO_XDP_SOCK:
        case PTR_TO_BTF_ID:
        case PTR_TO_BUF:
        case PTR_TO_PERCPU_BTF_ID:
        case PTR_TO_MEM:
            return true;
        default:
            return false;
    }
}

/* Does this register contain a constant zero? */
static bool register_is_null(struct bpf_reg_state *reg)
{
    return reg->type == SCALAR_VALUE && tnum_equals_const(reg->var_off, 0);
}

static bool register_is_const(struct bpf_reg_state *reg)
{
    return reg->type == SCALAR_VALUE && tnum_is_const(reg->var_off);
}

static bool __is_scalar_unbounded(struct bpf_reg_state *reg)
{
    return tnum_is_unknown(reg->var_off) && reg->smin_value == S64_MIN && reg->smax_value == S64_MAX &&
           reg->umin_value == 0 && reg->umax_value == U64_MAX && reg->s32_min_value == S32_MIN &&
           reg->s32_max_value == S32_MAX && reg->u32_min_value == 0 && reg->u32_max_value == U32_MAX;
}

static bool register_is_bounded(struct bpf_reg_state *reg)
{
    return reg->type == SCALAR_VALUE && !__is_scalar_unbounded(reg);
}

static bool __is_pointer_value(bool allow_ptr_leaks, const struct bpf_reg_state *reg)
{
    if (allow_ptr_leaks) {
        return false;
    }

    return reg->type != SCALAR_VALUE;
}

static void save_register_state(struct bpf_func_state *state, int spi, struct bpf_reg_state *reg)
{
    int i;

    state->stack[spi].spilled_ptr = *reg;
    state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;

    for (i = 0; i < BPF_REG_SIZE; i++) {
        state->stack[spi].slot_type[i] = STACK_SPILL;
    }
}

/* check_stack_{read,write}_fixed_off functions track spill/fill of registers,
 * stack boundary and alignment are checked in check_mem_access()
 */
static int check_stack_write_fixed_off(struct bpf_verifier_env *env,
                                       /* stack frame we're writing to */
                                       struct bpf_func_state *state, int off, int size, int value_regno, int insn_idx)
{
    struct bpf_func_state *cur; /* state of the current function */
    int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err;
    u32 dst_reg = env->prog->insnsi[insn_idx].dst_reg;
    struct bpf_reg_state *reg = NULL;

    err = realloc_func_state(state, round_up(slot + 1, BPF_REG_SIZE), state->acquired_refs, true);
    if (err) {
        return err;
    }
    /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
     * so it's aligned access and [off, off + size) are within stack limits
     */
    if (!env->allow_ptr_leaks && state->stack[spi].slot_type[0] == STACK_SPILL && size != BPF_REG_SIZE) {
        verbose(env, "attempt to corrupt spilled pointer on stack\n");
        return -EACCES;
    }

    cur = env->cur_state->frame[env->cur_state->curframe];
    if (value_regno >= 0) {
        reg = &cur->regs[value_regno];
    }
    if (!env->bypass_spec_v4) {
        bool sanitize = reg && is_spillable_regtype(reg->type);

        for (i = 0; i < size; i++) {
            if (state->stack[spi].slot_type[i] == STACK_INVALID) {
                sanitize = true;
                break;
            }
        }

        if (sanitize) {
            env->insn_aux_data[insn_idx].sanitize_stack_spill = true;
        }
    }

    if (reg && size == BPF_REG_SIZE && register_is_bounded(reg) && !register_is_null(reg) && env->bpf_capable) {
        if (dst_reg != BPF_REG_FP) {
            /* The backtracking logic can only recognize explicit
             * stack slot address like [fp - 8]. Other spill of
             * scalar via different register has to be conervative.
             * Backtrack from here and mark all registers as precise
             * that contributed into 'reg' being a constant.
             */
            err = mark_chain_precision(env, value_regno);
            if (err) {
                return err;
            }
        }
        save_register_state(state, spi, reg);
    } else if (reg && is_spillable_regtype(reg->type)) {
        /* register containing pointer is being spilled into stack */
        if (size != BPF_REG_SIZE) {
            verbose_linfo(env, insn_idx, "; ");
            verbose(env, "invalid size of register spill\n");
            return -EACCES;
        }
        if (state != cur && reg->type == PTR_TO_STACK) {
            verbose(env, "cannot spill pointers to stack into stack frame of the caller\n");
            return -EINVAL;
        }
        save_register_state(state, spi, reg);
    } else {
        u8 type = STACK_MISC;

        /* regular write of data into stack destroys any spilled ptr */
        state->stack[spi].spilled_ptr.type = NOT_INIT;
        /* Mark slots as STACK_MISC if they belonged to spilled ptr. */
        if (state->stack[spi].slot_type[0] == STACK_SPILL) {
            for (i = 0; i < BPF_REG_SIZE; i++) {
                state->stack[spi].slot_type[i] = STACK_MISC;
            }
        }

        /* only mark the slot as written if all 8 bytes were written
         * otherwise read propagation may incorrectly stop too soon
         * when stack slots are partially written.
         * This heuristic means that read propagation will be
         * conservative, since it will add reg_live_read marks
         * to stack slots all the way to first state when programs
         * writes+reads less than 8 bytes
         */
        if (size == BPF_REG_SIZE) {
            state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
        }

        /* when we zero initialize stack slots mark them as such */
        if (reg && register_is_null(reg)) {
            /* backtracking doesn't work for STACK_ZERO yet. */
            err = mark_chain_precision(env, value_regno);
            if (err) {
                return err;
            }
            type = STACK_ZERO;
        }

        /* Mark slots affected by this stack write. */
        for (i = 0; i < size; i++) {
            state->stack[spi].slot_type[(slot - i) % BPF_REG_SIZE] = type;
        }
    }
    return 0;
}

/* Write the stack: 'stack[ptr_regno + off] = value_regno'. 'ptr_regno' is
 * known to contain a variable offset.
 * This function checks whether the write is permitted and conservatively
 * tracks the effects of the write, considering that each stack slot in the
 * dynamic range is potentially written to.
 *
 * 'off' includes 'regno->off'.
 * 'value_regno' can be -1, meaning that an unknown value is being written to
 * the stack.
 *
 * Spilled pointers in range are not marked as written because we don't know
 * what's going to be actually written. This means that read propagation for
 * future reads cannot be terminated by this write.
 *
 * For privileged programs, uninitialized stack slots are considered
 * initialized by this write (even though we don't know exactly what offsets
 * are going to be written to). The idea is that we don't want the verifier to
 * reject future reads that access slots written to through variable offsets.
 */
static int check_stack_write_var_off(struct bpf_verifier_env *env,
                                     /* func where register points to */
                                     struct bpf_func_state *state, int ptr_regno, int off, int size, int value_regno,
                                     int insn_idx)
{
    struct bpf_func_state *cur; /* state of the current function */
    int min_off, max_off;
    int i, err;
    struct bpf_reg_state *ptr_reg = NULL, *value_reg = NULL;
    bool writing_zero = false;
    /* set if the fact that we're writing a zero is used to let any
     * stack slots remain STACK_ZERO
     */
    bool zero_used = false;

    cur = env->cur_state->frame[env->cur_state->curframe];
    ptr_reg = &cur->regs[ptr_regno];
    min_off = ptr_reg->smin_value + off;
    max_off = ptr_reg->smax_value + off + size;
    if (value_regno >= 0) {
        value_reg = &cur->regs[value_regno];
    }
    if (value_reg && register_is_null(value_reg)) {
        writing_zero = true;
    }

    err = realloc_func_state(state, round_up(-min_off, BPF_REG_SIZE), state->acquired_refs, true);
    if (err) {
        return err;
    }

    /* Variable offset writes destroy any spilled pointers in range. */
    for (i = min_off; i < max_off; i++) {
        u8 new_type, *stype;
        int slot, spi;

        slot = -i - 1;
        spi = slot / BPF_REG_SIZE;
        stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];

        if (!env->allow_ptr_leaks && *stype != NOT_INIT && *stype != SCALAR_VALUE) {
            /* Reject the write if there's are spilled pointers in
             * range. If we didn't reject here, the ptr status
             * would be erased below (even though not all slots are
             * actually overwritten), possibly opening the door to
             * leaks.
             */
            verbose(env, "spilled ptr in range of var-offset stack write; insn %d, ptr off: %d", insn_idx, i);
            return -EINVAL;
        }

        /* Erase all spilled pointers. */
        state->stack[spi].spilled_ptr.type = NOT_INIT;

        /* Update the slot type. */
        new_type = STACK_MISC;
        if (writing_zero && *stype == STACK_ZERO) {
            new_type = STACK_ZERO;
            zero_used = true;
        }
        /* If the slot is STACK_INVALID, we check whether it's OK to
         * pretend that it will be initialized by this write. The slot
         * might not actually be written to, and so if we mark it as
         * initialized future reads might leak uninitialized memory.
         * For privileged programs, we will accept such reads to slots
         * that may or may not be written because, if we're reject
         * them, the error would be too confusing.
         */
        if (*stype == STACK_INVALID && !env->allow_uninit_stack) {
            verbose(env, "uninit stack in range of var-offset write prohibited for !root; insn %d, off: %d", insn_idx,
                    i);
            return -EINVAL;
        }
        *stype = new_type;
    }
    if (zero_used) {
        /* backtracking doesn't work for STACK_ZERO yet. */
        err = mark_chain_precision(env, value_regno);
        if (err) {
            return err;
        }
    }
    return 0;
}

/* When register 'dst_regno' is assigned some values from stack[min_off,
 * max_off), we set the register's type according to the types of the
 * respective stack slots. If all the stack values are known to be zeros, then
 * so is the destination reg. Otherwise, the register is considered to be
 * SCALAR. This function does not deal with register filling; the caller must
 * ensure that all spilled registers in the stack range have been marked as
 * read.
 */
static void mark_reg_stack_read(struct bpf_verifier_env *env,
                                /* func where src register points to */
                                struct bpf_func_state *ptr_state, int min_off, int max_off, int dst_regno)
{
    struct bpf_verifier_state *vstate = env->cur_state;
    struct bpf_func_state *state = vstate->frame[vstate->curframe];
    int i, slot, spi;
    u8 *stype;
    int zeros = 0;

    for (i = min_off; i < max_off; i++) {
        slot = -i - 1;
        spi = slot / BPF_REG_SIZE;
        stype = ptr_state->stack[spi].slot_type;
        if (stype[slot % BPF_REG_SIZE] != STACK_ZERO) {
            break;
        }
        zeros++;
    }
    if (zeros == max_off - min_off) {
        /* any access_size read into register is zero extended,
         * so the whole register == const_zero
         */
        verifier_mark_reg_const_zero(&state->regs[dst_regno]);
        /* backtracking doesn't support STACK_ZERO yet,
         * so mark it precise here, so that later
         * backtracking can stop here.
         * Backtracking may not need this if this register
         * doesn't participate in pointer adjustment.
         * Forward propagation of precise flag is not
         * necessary either. This mark is only to stop
         * backtracking. Any register that contributed
         * to const 0 was marked precise before spill.
         */
        state->regs[dst_regno].precise = true;
    } else {
        /* have read misc data from the stack */
        mark_reg_unknown(env, state->regs, dst_regno);
    }
    state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
}

/* Read the stack at 'off' and put the results into the register indicated by
 * 'dst_regno'. It handles reg filling if the addressed stack slot is a
 * spilled reg.
 *
 * 'dst_regno' can be -1, meaning that the read value is not going to a
 * register.
 *
 * The access is assumed to be within the current stack bounds.
 */
static int check_stack_read_fixed_off(struct bpf_verifier_env *env,
                                      /* func where src register points to */
                                      struct bpf_func_state *reg_state, int off, int size, int dst_regno)
{
    struct bpf_verifier_state *vstate = env->cur_state;
    struct bpf_func_state *state = vstate->frame[vstate->curframe];
    int i, slot = -off - 1, spi = slot / BPF_REG_SIZE;
    struct bpf_reg_state *reg;
    u8 *stype;

    stype = reg_state->stack[spi].slot_type;
    reg = &reg_state->stack[spi].spilled_ptr;

    if (stype[0] == STACK_SPILL) {
        if (size != BPF_REG_SIZE) {
            if (reg->type != SCALAR_VALUE) {
                verbose_linfo(env, env->insn_idx, "; ");
                verbose(env, "invalid size of register fill\n");
                return -EACCES;
            }
            if (dst_regno >= 0) {
                mark_reg_unknown(env, state->regs, dst_regno);
                state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
            }
            mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
            return 0;
        }
        for (i = 1; i < BPF_REG_SIZE; i++) {
            if (stype[(slot - i) % BPF_REG_SIZE] != STACK_SPILL) {
                verbose(env, "corrupted spill memory\n");
                return -EACCES;
            }
        }

        if (dst_regno >= 0) {
            /* restore register state from stack */
            state->regs[dst_regno] = *reg;
            /* mark reg as written since spilled pointer state likely
             * has its liveness marks cleared by is_state_visited()
             * which resets stack/reg liveness for state transitions
             */
            state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
        } else if (__is_pointer_value(env->allow_ptr_leaks, reg)) {
            /* If dst_regno==-1, the caller is asking us whether
             * it is acceptable to use this value as a SCALAR_VALUE
             * (e.g. for XADD).
             * We must not allow unprivileged callers to do that
             * with spilled pointers.
             */
            verbose(env, "leaking pointer from stack off %d\n", off);
            return -EACCES;
        }
        mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
    } else {
        u8 type;

        for (i = 0; i < size; i++) {
            type = stype[(slot - i) % BPF_REG_SIZE];
            if (type == STACK_MISC) {
                continue;
            }
            if (type == STACK_ZERO) {
                continue;
            }
            verbose(env, "invalid read from stack off %d+%d size %d\n", off, i, size);
            return -EACCES;
        }
        mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
        if (dst_regno >= 0) {
            mark_reg_stack_read(env, reg_state, off, off + size, dst_regno);
        }
    }
    return 0;
}

enum stack_access_src {
    ACCESS_DIRECT = 1, /* the access is performed by an instruction */
    ACCESS_HELPER = 2, /* the access is performed by a helper */
};

static int check_stack_range_initialized(struct bpf_verifier_env *env, int regno, int off, int access_size,
                                         bool zero_size_allowed, enum stack_access_src type,
                                         struct bpf_call_arg_meta *meta);

static struct bpf_reg_state *reg_state(struct bpf_verifier_env *env, int regno)
{
    return cur_regs(env) + regno;
}

/* Read the stack at 'ptr_regno + off' and put the result into the register
 * 'dst_regno'.
 * 'off' includes the pointer register's fixed offset(i.e. 'ptr_regno.off'),
 * but not its variable offset.
 * 'size' is assumed to be <= reg size and the access is assumed to be aligned.
 *
 * As opposed to check_stack_read_fixed_off, this function doesn't deal with
 * filling registers (i.e. reads of spilled register cannot be detected when
 * the offset is not fixed). We conservatively mark 'dst_regno' as containing
 * SCALAR_VALUE. That's why we assert that the 'ptr_regno' has a variable
 * offset; for a fixed offset check_stack_read_fixed_off should be used
 * instead.
 */
static int check_stack_read_var_off(struct bpf_verifier_env *env, int ptr_regno, int off, int size, int dst_regno)
{
    /* The state of the source register. */
    struct bpf_reg_state *reg = reg_state(env, ptr_regno);
    struct bpf_func_state *ptr_state = func(env, reg);
    int err;
    int min_off, max_off;

    /* Note that we pass a NULL meta, so raw access will not be permitted.
     */
    err = check_stack_range_initialized(env, ptr_regno, off, size, false, ACCESS_DIRECT, NULL);
    if (err) {
        return err;
    }

    min_off = reg->smin_value + off;
    max_off = reg->smax_value + off;
    mark_reg_stack_read(env, ptr_state, min_off, max_off + size, dst_regno);
    return 0;
}

/* check_stack_read dispatches to check_stack_read_fixed_off or
 * check_stack_read_var_off.
 *
 * The caller must ensure that the offset falls within the allocated stack
 * bounds.
 *
 * 'dst_regno' is a register which will receive the value from the stack. It
 * can be -1, meaning that the read value is not going to a register.
 */
static int check_stack_read(struct bpf_verifier_env *env, int ptr_regno, int off, int size, int dst_regno)
{
    struct bpf_reg_state *reg = reg_state(env, ptr_regno);
    struct bpf_func_state *state = func(env, reg);
    int err;
    /* Some accesses are only permitted with a static offset. */
    bool var_off = !tnum_is_const(reg->var_off);
    /* The offset is required to be static when reads don't go to a
     * register, in order to not leak pointers (see
     * check_stack_read_fixed_off).
     */
    if (dst_regno < 0 && var_off) {
        char tn_buf[48];

        tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
        verbose(env, "variable offset stack pointer cannot be passed into helper function; var_off=%s off=%d size=%d\n",
                tn_buf, off, size);
        return -EACCES;
    }
    /* Variable offset is prohibited for unprivileged mode for simplicity
     * since it requires corresponding support in Spectre masking for stack
     * ALU. See also retrieve_ptr_limit().
     */
    if (!env->bypass_spec_v1 && var_off) {
        char tn_buf[48];

        tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
        verbose(env, "R%d variable offset stack access prohibited for !root, var_off=%s\n", ptr_regno, tn_buf);
        return -EACCES;
    }

    if (!var_off) {
        off += reg->var_off.value;
        err = check_stack_read_fixed_off(env, state, off, size, dst_regno);
    } else {
        /* Variable offset stack reads need more conservative handling
         * than fixed offset ones. Note that dst_regno >= 0 on this
         * branch.
         */
        err = check_stack_read_var_off(env, ptr_regno, off, size, dst_regno);
    }
    return err;
}

/* check_stack_write dispatches to check_stack_write_fixed_off or
 * check_stack_write_var_off.
 *
 * 'ptr_regno' is the register used as a pointer into the stack.
 * 'off' includes 'ptr_regno->off', but not its variable offset (if any).
 * 'value_regno' is the register whose value we're writing to the stack. It can
 * be -1, meaning that we're not writing from a register.
 *
 * The caller must ensure that the offset falls within the maximum stack size.
 */
static int check_stack_write(struct bpf_verifier_env *env, int ptr_regno, int off, int size, int value_regno,
                             int insn_idx)
{
    struct bpf_reg_state *reg = reg_state(env, ptr_regno);
    struct bpf_func_state *state = func(env, reg);
    int err;

    if (tnum_is_const(reg->var_off)) {
        off += reg->var_off.value;
        err = check_stack_write_fixed_off(env, state, off, size, value_regno, insn_idx);
    } else {
        /* Variable offset stack reads need more conservative handling
         * than fixed offset ones.
         */
        err = check_stack_write_var_off(env, state, ptr_regno, off, size, value_regno, insn_idx);
    }
    return err;
}

static int check_map_access_type(struct bpf_verifier_env *env, u32 regno, int off, int size, enum bpf_access_type type)
{
    struct bpf_reg_state *regs = cur_regs(env);
    struct bpf_map *map = regs[regno].map_ptr;
    u32 cap = bpf_map_flags_to_cap(map);
    if (type == BPF_WRITE && !(cap & BPF_MAP_CAN_WRITE)) {
        verbose(env, "write into map forbidden, value_size=%d off=%d size=%d\n", map->value_size, off, size);
        return -EACCES;
    }
    if (type == BPF_READ && !(cap & BPF_MAP_CAN_READ)) {
        verbose(env, "read from map forbidden, value_size=%d off=%d size=%d\n", map->value_size, off, size);
        return -EACCES;
    }

    return 0;
}

/* check read/write into memory region (e.g., map value, ringbuf sample, etc) */
static int __check_mem_access(struct bpf_verifier_env *env, int regno, int off, int size, u32 mem_size,
                              bool zero_size_allowed)
{
    bool size_ok = size > 0 || (size == 0 && zero_size_allowed);
    struct bpf_reg_state *reg;

    if (off >= 0 && size_ok && (u64)off + size <= mem_size) {
        return 0;
    }

    reg = &cur_regs(env)[regno];
    switch (reg->type) {
        case PTR_TO_MAP_VALUE:
            verbose(env, "invalid access to map value, value_size=%d off=%d size=%d\n", mem_size, off, size);
            break;
        case PTR_TO_PACKET:
        case PTR_TO_PACKET_META:
        case PTR_TO_PACKET_END:
            verbose(env, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n", off, size, regno,
                    reg->id, off, mem_size);
            break;
        case PTR_TO_MEM:
        default:
            verbose(env, "invalid access to memory, mem_size=%u off=%d size=%d\n", mem_size, off, size);
    }

    return -EACCES;
}

/* check read/write into a memory region with possible variable offset */
static int check_mem_region_access(struct bpf_verifier_env *env, u32 regno, int off, int size, u32 mem_size,
                                   bool zero_size_allowed)
{
    struct bpf_verifier_state *vstate = env->cur_state;
    struct bpf_func_state *state = vstate->frame[vstate->curframe];
    struct bpf_reg_state *reg = &state->regs[regno];
    int err;

    /* We may have adjusted the register pointing to memory region, so we
     * need to try adding each of min_value and max_value to off
     * to make sure our theoretical access will be safe.
     */
    if (env->log.level & BPF_LOG_LEVEL) {
        print_verifier_state(env, state);
    }

    /* The minimum value is only important with signed
     * comparisons where we can't assume the floor of a
     * value is 0.  If we are using signed variables for our
     * index'es we need to make sure that whatever we use
     * will have a set floor within our range.
     */
    if (reg->smin_value < 0 &&
        (reg->smin_value == S64_MIN || (off + reg->smin_value != (s64)(s32)(off + reg->smin_value)) ||
         reg->smin_value + off < 0)) {
        verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", regno);
        return -EACCES;
    }
    err = __check_mem_access(env, regno, reg->smin_value + off, size, mem_size, zero_size_allowed);
    if (err) {
        verbose(env, "R%d min value is outside of the allowed memory range\n", regno);
        return err;
    }

    /* If we haven't set a max value then we need to bail since we can't be
     * sure we won't do bad things.
     * If reg->umax_value + off could overflow, treat that as unbounded too.
     */
    if (reg->umax_value >= BPF_MAX_VAR_OFF) {
        verbose(env, "R%d unbounded memory access, make sure to bounds check any such access\n", regno);
        return -EACCES;
    }
    err = __check_mem_access(env, regno, reg->umax_value + off, size, mem_size, zero_size_allowed);
    if (err) {
        verbose(env, "R%d max value is outside of the allowed memory range\n", regno);
        return err;
    }

    return 0;
}

/* check read/write into a map element with possible variable offset */
static int check_map_access(struct bpf_verifier_env *env, u32 regno, int off, int size, bool zero_size_allowed)
{
    struct bpf_verifier_state *vstate = env->cur_state;
    struct bpf_func_state *state = vstate->frame[vstate->curframe];
    struct bpf_reg_state *reg = &state->regs[regno];
    struct bpf_map *map = reg->map_ptr;
    int err;

    err = check_mem_region_access(env, regno, off, size, map->value_size, zero_size_allowed);
    if (err) {
        return err;
    }

    if (map_value_has_spin_lock(map)) {
        u32 lock = map->spin_lock_off;

        /* if any part of struct bpf_spin_lock can be touched by
         * load/store reject this program.
         * To check that [x1, x2) overlaps with [y1, y2)
         * it is sufficient to check x1 < y2 && y1 < x2.
         */
        if (reg->smin_value + off < lock + sizeof(struct bpf_spin_lock) && lock < reg->umax_value + off + size) {
            verbose(env, "bpf_spin_lock cannot be accessed directly by load/store\n");
            return -EACCES;
        }
    }
    return err;
}

#define MAX_PACKET_OFF 0xffff

static enum bpf_prog_type resolve_prog_type(struct bpf_prog *prog)
{
    return prog->aux->dst_prog ? prog->aux->dst_prog->type : prog->type;
}

static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, const struct bpf_call_arg_meta *meta,
                                       enum bpf_access_type t)
{
    enum bpf_prog_type prog_type = resolve_prog_type(env->prog);

    switch (prog_type) {
        /* Program types only with direct read access go here! */
        case BPF_PROG_TYPE_LWT_IN:
        case BPF_PROG_TYPE_LWT_OUT:
        case BPF_PROG_TYPE_LWT_SEG6LOCAL:
        case BPF_PROG_TYPE_SK_REUSEPORT:
        case BPF_PROG_TYPE_FLOW_DISSECTOR:
        case BPF_PROG_TYPE_CGROUP_SKB:
            if (t == BPF_WRITE) {
                return false;
            }
            fallthrough;

        /* Program types with direct read + write access go here! */
        case BPF_PROG_TYPE_SCHED_CLS:
        case BPF_PROG_TYPE_SCHED_ACT:
        case BPF_PROG_TYPE_XDP:
        case BPF_PROG_TYPE_LWT_XMIT:
        case BPF_PROG_TYPE_SK_SKB:
        case BPF_PROG_TYPE_SK_MSG:
            if (meta) {
                return meta->pkt_access;
            }

            env->seen_direct_write = true;
            return true;

        case BPF_PROG_TYPE_CGROUP_SOCKOPT:
            if (t == BPF_WRITE) {
                env->seen_direct_write = true;
            }

            return true;

        default:
            return false;
    }
}

static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off, int size, bool zero_size_allowed)
{
    struct bpf_reg_state *regs = cur_regs(env);
    struct bpf_reg_state *reg = &regs[regno];
    int err;

    /* We may have added a variable offset to the packet pointer; but any
     * reg->range we have comes after that.  We are only checking the fixed
     * offset.
     */

    /* We don't allow negative numbers, because we aren't tracking enough
     * detail to prove they're safe.
     */
    if (reg->smin_value < 0) {
        verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", regno);
        return -EACCES;
    }
    err = __check_mem_access(env, regno, off, size, reg->range, zero_size_allowed);
    if (err) {
        verbose(env, "R%d offset is outside of the packet\n", regno);
        return err;
    }

    /* __check_mem_access has made sure "off + size - 1" is within u16.
     * reg->umax_value can't be bigger than MAX_PACKET_OFF which is 0xffff,
     * otherwise find_good_pkt_pointers would have refused to set range info
     * that __check_mem_access would have rejected this pkt access.
     * Therefore, "off + reg->umax_value + size - 1" won't overflow u32.
     */
    env->prog->aux->max_pkt_offset = max_t(u32, env->prog->aux->max_pkt_offset, off + reg->umax_value + size - 1);

    return err;
}

/* check access to 'struct bpf_context' fields.  Supports fixed offsets only */
static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size, enum bpf_access_type t,
                            enum bpf_reg_type *reg_type, u32 *btf_id)
{
    struct bpf_insn_access_aux info = {
        .reg_type = *reg_type,
        .log = &env->log,
    };

    if (env->ops->is_valid_access && env->ops->is_valid_access(off, size, t, env->prog, &info)) {
        /* A non zero info.ctx_field_size indicates that this field is a
         * candidate for later verifier transformation to load the whole
         * field and then apply a mask when accessed with a narrower
         * access than actual ctx access size. A zero info.ctx_field_size
         * will only allow for whole field access and rejects any other
         * type of narrower access.
         */
        *reg_type = info.reg_type;

        if (base_type(*reg_type) == PTR_TO_BTF_ID) {
            *btf_id = info.btf_id;
        } else {
            env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size;
        }
        /* remember the offset of last byte accessed in ctx */
        if (env->prog->aux->max_ctx_offset < off + size) {
            env->prog->aux->max_ctx_offset = off + size;
        }
        return 0;
    }

    verbose(env, "invalid bpf_context access off=%d size=%d\n", off, size);
    return -EACCES;
}

static int check_flow_keys_access(struct bpf_verifier_env *env, int off, int size)
{
    if (size < 0 || off < 0 || (u64)off + size > sizeof(struct bpf_flow_keys)) {
        verbose(env, "invalid access to flow keys off=%d size=%d\n", off, size);
        return -EACCES;
    }
    return 0;
}

static int check_sock_access(struct bpf_verifier_env *env, int insn_idx, u32 regno, int off, int size,
                             enum bpf_access_type t)
{
    struct bpf_reg_state *regs = cur_regs(env);
    struct bpf_reg_state *reg = &regs[regno];
    struct bpf_insn_access_aux info = {};
    bool valid;

    if (reg->smin_value < 0) {
        verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", regno);
        return -EACCES;
    }

    switch (reg->type) {
        case PTR_TO_SOCK_COMMON:
            valid = bpf_sock_common_is_valid_access(off, size, t, &info);
            break;
        case PTR_TO_SOCKET:
            valid = bpf_sock_is_valid_access(off, size, t, &info);
            break;
        case PTR_TO_TCP_SOCK:
            valid = bpf_tcp_sock_is_valid_access(off, size, t, &info);
            break;
        case PTR_TO_XDP_SOCK:
            valid = bpf_xdp_sock_is_valid_access(off, size, t, &info);
            break;
        default:
            valid = false;
    }

    if (valid) {
        env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size;
        return 0;
    }

    verbose(env, "R%d invalid %s access off=%d size=%d\n", regno, reg_type_str(env, reg->type), off, size);

    return -EACCES;
}

static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
{
    return __is_pointer_value(env->allow_ptr_leaks, reg_state(env, regno));
}

static bool is_ctx_reg(struct bpf_verifier_env *env, int regno)
{
    const struct bpf_reg_state *reg = reg_state(env, regno);

    return reg->type == PTR_TO_CTX;
}

static bool is_sk_reg(struct bpf_verifier_env *env, int regno)
{
    const struct bpf_reg_state *reg = reg_state(env, regno);

    return type_is_sk_pointer(reg->type);
}

static bool is_pkt_reg(struct bpf_verifier_env *env, int regno)
{
    const struct bpf_reg_state *reg = reg_state(env, regno);

    return type_is_pkt_pointer(reg->type);
}

static bool is_flow_key_reg(struct bpf_verifier_env *env, int regno)
{
    const struct bpf_reg_state *reg = reg_state(env, regno);

    /* Separate to is_ctx_reg() since we still want to allow BPF_ST here. */
    return reg->type == PTR_TO_FLOW_KEYS;
}

static int check_pkt_ptr_alignment(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, int off, int size,
                                   bool strict)
{
    struct tnum reg_off;
    int ip_align;

    /* Byte size accesses are always allowed. */
    if (!strict || size == 1) {
        return 0;
    }

    /* For platforms that do not have a Kconfig enabling
     * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
     * NET_IP_ALIGN is universally set to '2'.  And on platforms
     * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
     * to this code only in strict mode where we want to emulate
     * the NET_IP_ALIGN==2 checking.  Therefore use an
     * unconditional IP align value of '2'.
     */
    ip_align = 2;

    reg_off = tnum_add(reg->var_off, tnum_const(ip_align + reg->off + off));
    if (!tnum_is_aligned(reg_off, size)) {
        char tn_buf[48];

        tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
        verbose(env, "misaligned packet access off %d+%s+%d+%d size %d\n", ip_align, tn_buf, reg->off, off, size);
        return -EACCES;
    }

    return 0;
}

static int check_generic_ptr_alignment(struct bpf_verifier_env *env, const struct bpf_reg_state *reg,
                                       const char *pointer_desc, int off, int size, bool strict)
{
    struct tnum reg_off;

    /* Byte size accesses are always allowed. */
    if (!strict || size == 1) {
        return 0;
    }

    reg_off = tnum_add(reg->var_off, tnum_const(reg->off + off));
    if (!tnum_is_aligned(reg_off, size)) {
        char tn_buf[48];

        tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
        verbose(env, "misaligned %saccess off %s+%d+%d size %d\n", pointer_desc, tn_buf, reg->off, off, size);
        return -EACCES;
    }

    return 0;
}

static int check_ptr_alignment(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, int off, int size,
                               bool strict_alignment_once)
{
    bool strict = env->strict_alignment || strict_alignment_once;
    const char *pointer_desc = "";

    switch (reg->type) {
        case PTR_TO_PACKET:
        case PTR_TO_PACKET_META:
            /* Special case, because of NET_IP_ALIGN. Given metadata sits
             * right in front, treat it the very same way.
             */
            return check_pkt_ptr_alignment(env, reg, off, size, strict);
        case PTR_TO_FLOW_KEYS:
            pointer_desc = "flow keys ";
            break;
        case PTR_TO_MAP_VALUE:
            pointer_desc = "value ";
            break;
        case PTR_TO_CTX:
            pointer_desc = "context ";
            break;
        case PTR_TO_STACK:
            pointer_desc = "stack ";
            /* The stack spill tracking logic in check_stack_write_fixed_off()
             * and check_stack_read_fixed_off() relies on stack accesses being
             * aligned.
             */
            strict = true;
            break;
        case PTR_TO_SOCKET:
            pointer_desc = "sock ";
            break;
        case PTR_TO_SOCK_COMMON:
            pointer_desc = "sock_common ";
            break;
        case PTR_TO_TCP_SOCK:
            pointer_desc = "tcp_sock ";
            break;
        case PTR_TO_XDP_SOCK:
            pointer_desc = "xdp_sock ";
            break;
        default:
            break;
    }
    return check_generic_ptr_alignment(env, reg, pointer_desc, off, size, strict);
}

static int update_stack_depth(struct bpf_verifier_env *env, const struct bpf_func_state *func, int off)
{
    u16 stack = env->subprog_info[func->subprogno].stack_depth;

    if (stack >= -off) {
        return 0;
    }

    /* update known max for given subprogram */
    env->subprog_info[func->subprogno].stack_depth = -off;
    return 0;
}

/* starting from main bpf function walk all instructions of the function
 * and recursively walk all callees that given function can call.
 * Ignore jump and exit insns.
 * Since recursion is prevented by check_cfg() this algorithm
 * only needs a local stack of MAX_CALL_FRAMES to remember callsites
 */
static int check_max_stack_depth(struct bpf_verifier_env *env)
{
    int depth = 0, frame = 0, idx = 0, i = 0, subprog_end;
    struct bpf_subprog_info *subprog = env->subprog_info;
    struct bpf_insn *insn = env->prog->insnsi;
    bool tail_call_reachable = false;
    int ret_insn[MAX_CALL_FRAMES];
    int ret_prog[MAX_CALL_FRAMES];
    int j;
    int process_flag = 0;
    int continue_flag = 0;

    while (1) {
        if (process_flag == 0 && continue_flag == 0) {
            /* protect against potential stack overflow that might happen when
             * bpf2bpf calls get combined with tailcalls. Limit the caller's stack
             * depth for such case down to 256 so that the worst case scenario
             * would result in 8k stack size (32 which is tailcall limit * 256 =
             * 8k).
             *
             * To get the idea what might happen, see an example:
             * func1 -> sub rsp, 128
             *  subfunc1 -> sub rsp, 256
             *  tailcall1 -> add rsp, 256
             *   func2 -> sub rsp, 192 (total stack size = 128 + 192 = 320)
             *   subfunc2 -> sub rsp, 64
             *   subfunc22 -> sub rsp, 128
             *   tailcall2 -> add rsp, 128
             *    func3 -> sub rsp, 32 (total stack size 128 + 192 + 64 + 32 = 416)
             *
             * tailcall will unwind the current stack frame but it will not get rid
             * of caller's stack as shown on the example above.
             */
            if (idx && subprog[idx].has_tail_call && depth >= VERIFIER_TWOHUNDREDFIFTYSIX) {
                verbose(env, "tail_calls are not allowed when call stack of previous frames is %d bytes. Too large\n",
                        depth);
                return -EACCES;
            }
            /* round up to 32-bytes, since this is granularity
             * of interpreter stack size
             */
            depth += round_up(max_t(u32, subprog[idx].stack_depth, 1), VERIFIER_THIRTYTWO);
            if (depth > MAX_BPF_STACK) {
                verbose(env, "combined stack size of %d calls is %d. Too large\n", frame + 1, depth);
                return -EACCES;
            }
        }
        while (1) {
            continue_flag = 0;
            subprog_end = subprog[idx + 1].start;
            for (; i < subprog_end; i++) {
                if (insn[i].code != (BPF_JMP | BPF_CALL)) {
                    continue;
                }
                if (insn[i].src_reg != BPF_PSEUDO_CALL) {
                    continue;
                }
                /* remember insn and function to return to */
                ret_insn[frame] = i + 1;
                ret_prog[frame] = idx;

                /* find the callee */
                i = i + insn[i].imm + 1;
                idx = find_subprog(env, i);
                if (idx < 0) {
                    WARN_ONCE(1, "verifier bug. No program starts at insn %d\n", i);
                    return -EFAULT;
                }

                if (subprog[idx].has_tail_call) {
                    tail_call_reachable = true;
                }

                frame++;
                if (frame >= MAX_CALL_FRAMES) {
                    verbose(env, "the call stack of %d frames is too deep !\n", frame);
                    return -E2BIG;
                }
                process_flag = 1;
                break;
            }
            if (process_flag == 1) {
                break;
            }
        }
        if (process_flag == 1) {
            process_flag = 0;
            continue;
        }
        /* if tail call got detected across bpf2bpf calls then mark each of the
         * currently present subprog frames as tail call reachable subprogs;
         * this info will be utilized by JIT so that we will be preserving the
         * tail call counter throughout bpf2bpf calls combined with tailcalls
         */
        if (tail_call_reachable) {
            for (j = 0; j < frame; j++) {
                subprog[ret_prog[j]].tail_call_reachable = true;
            }
        }
        if (subprog[0].tail_call_reachable) {
            env->prog->aux->tail_call_reachable = true;
        }

        /* end of for() loop means the last insn of the 'subprog'
         * was reached. Doesn't matter whether it was JA or EXIT
         */
        if (frame == 0) {
            return 0;
        }
        depth -= round_up(max_t(u32, subprog[idx].stack_depth, 1), VERIFIER_THIRTYTWO);
        frame--;
        i = ret_insn[frame];
        idx = ret_prog[frame];
        continue_flag = 1;
        continue;
    }
}

#ifndef CONFIG_BPF_JIT_ALWAYS_ON
static int get_callee_stack_depth(struct bpf_verifier_env *env, const struct bpf_insn *insn, int idx)
{
    int start = idx + insn->imm + 1, subprog;

    subprog = find_subprog(env, start);
    if (subprog < 0) {
        WARN_ONCE(1, "verifier bug. No program starts at insn %d\n", start);
        return -EFAULT;
    }
    return env->subprog_info[subprog].stack_depth;
}
#endif

static int __check_ptr_off_reg(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, int regno,
                               bool fixed_off_ok)
{
    /* Access to this pointer-typed register or passing it to a helper
     * is only allowed in its original, unmodified form.
     */

    if (!fixed_off_ok && reg->off) {
        verbose(env, "dereference of modified %s ptr R%d off=%d disallowed\n", reg_type_str(env, reg->type), regno,
                reg->off);
        return -EACCES;
    }

    if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
        char tn_buf[48];

        tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
        verbose(env, "variable %s access var_off=%s disallowed\n", reg_type_str(env, reg->type), tn_buf);
        return -EACCES;
    }

    return 0;
}

int check_ptr_off_reg(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, int regno)
{
    return __check_ptr_off_reg(env, reg, regno, false);
}

static int __check_buffer_access(struct bpf_verifier_env *env, const char *buf_info, const struct bpf_reg_state *reg,
                                 int regno, int off, int size)
{
    if (off < 0) {
        verbose(env, "R%d invalid %s buffer access: off=%d, size=%d\n", regno, buf_info, off, size);
        return -EACCES;
    }
    if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
        char tn_buf[48];

        tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
        verbose(env, "R%d invalid variable buffer offset: off=%d, var_off=%s\n", regno, off, tn_buf);
        return -EACCES;
    }

    return 0;
}

static int check_tp_buffer_access(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, int regno, int off,
                                  int size)
{
    int err;

    err = __check_buffer_access(env, "tracepoint", reg, regno, off, size);
    if (err) {
        return err;
    }

    if (off + size > env->prog->aux->max_tp_access) {
        env->prog->aux->max_tp_access = off + size;
    }

    return 0;
}

static int check_buffer_access(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, int regno, int off,
                               int size, bool zero_size_allowed, const char *buf_info, u32 *max_access)
{
    int err;

    err = __check_buffer_access(env, buf_info, reg, regno, off, size);
    if (err) {
        return err;
    }

    if (off + size > *max_access) {
        *max_access = off + size;
    }

    return 0;
}

/* BPF architecture zero extends alu32 ops into 64-bit registesr */
static void zext_32_to_64(struct bpf_reg_state *reg)
{
    reg->var_off = tnum_subreg(reg->var_off);
    verifier_reg_assign_32_into_64(reg);
}

/* truncate register to smaller size (in bytes)
 * must be called with size < BPF_REG_SIZE
 */
static void coerce_reg_to_size(struct bpf_reg_state *reg, int size)
{
    u64 mask;

    /* clear high bits in bit representation */
    reg->var_off = tnum_cast(reg->var_off, size);

    /* fix arithmetic bounds */
    mask = ((u64)1 << (size * VERIFIER_EIGHT)) - 1;
    if ((reg->umin_value & ~mask) == (reg->umax_value & ~mask)) {
        reg->umin_value &= mask;
        reg->umax_value &= mask;
    } else {
        reg->umin_value = 0;
        reg->umax_value = mask;
    }
    reg->smin_value = reg->umin_value;
    reg->smax_value = reg->umax_value;

    /* If size is smaller than 32bit register the 32bit register
     * values are also truncated so we push 64-bit bounds into
     * 32-bit bounds. Above were truncated < 32-bits already.
     */
    if (size >= VERIFIER_FOUR) {
        return;
    }
    __reg_combine_64_into_32(reg);
}

static bool bpf_map_is_rdonly(const struct bpf_map *map)
{
    return (map->map_flags & BPF_F_RDONLY_PROG) && map->frozen;
}

static int bpf_map_direct_read(struct bpf_map *map, int off, int size, u64 *val)
{
    void *ptr;
    u64 addr;
    int err;

    err = map->ops->map_direct_value_addr(map, &addr, off);
    if (err) {
        return err;
    }
    ptr = (void *)(long)addr + off;

    switch (size) {
        case sizeof(u8):
            *val = (u64) * (u8 *)ptr;
            break;
        case sizeof(u16):
            *val = (u64) * (u16 *)ptr;
            break;
        case sizeof(u32):
            *val = (u64) * (u32 *)ptr;
            break;
        case sizeof(u64):
            *val = *(u64 *)ptr;
            break;
        default:
            return -EINVAL;
    }
    return 0;
}

static int check_ptr_to_btf_access(struct bpf_verifier_env *env, struct bpf_reg_state *regs, int regno, int off,
                                   int size, enum bpf_access_type atype, int value_regno)
{
    struct bpf_reg_state *reg = regs + regno;
    const struct btf_type *t = btf_type_by_id(btf_vmlinux, reg->btf_id);
    const char *tname = btf_name_by_offset(btf_vmlinux, t->name_off);
    u32 btf_id;
    int ret;

    if (off < 0) {
        verbose(env, "R%d is ptr_%s invalid negative access: off=%d\n", regno, tname, off);
        return -EACCES;
    }
    if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
        char tn_buf[48];

        tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
        verbose(env, "R%d is ptr_%s invalid variable offset: off=%d, var_off=%s\n", regno, tname, off, tn_buf);
        return -EACCES;
    }

    if (env->ops->btf_struct_access) {
        ret = env->ops->btf_struct_access(&env->log, t, off, size, atype, &btf_id);
    } else {
        if (atype != BPF_READ) {
            verbose(env, "only read is supported\n");
            return -EACCES;
        }

        ret = btf_struct_access(&env->log, t, off, size, atype, &btf_id);
    }

    if (ret < 0) {
        return ret;
    }

    if (atype == BPF_READ && value_regno >= 0) {
        mark_btf_ld_reg(env, regs, value_regno, ret, btf_id);
    }

    return 0;
}

static int check_ptr_to_map_access(struct bpf_verifier_env *env, struct bpf_reg_state *regs, int regno, int off,
                                   int size, enum bpf_access_type atype, int value_regno)
{
    struct bpf_reg_state *reg = regs + regno;
    struct bpf_map *map = reg->map_ptr;
    const struct btf_type *t;
    const char *tname;
    u32 btf_id;
    int ret;

    if (!btf_vmlinux) {
        verbose(env, "map_ptr access not supported without CONFIG_DEBUG_INFO_BTF\n");
        return -ENOTSUPP;
    }

    if (!map->ops->map_btf_id || !*map->ops->map_btf_id) {
        verbose(env, "map_ptr access not supported for map type %d\n", map->map_type);
        return -ENOTSUPP;
    }

    t = btf_type_by_id(btf_vmlinux, *map->ops->map_btf_id);
    tname = btf_name_by_offset(btf_vmlinux, t->name_off);

    if (!env->allow_ptr_to_map_access) {
        verbose(env, "%s access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n", tname);
        return -EPERM;
    }

    if (off < 0) {
        verbose(env, "R%d is %s invalid negative access: off=%d\n", regno, tname, off);
        return -EACCES;
    }

    if (atype != BPF_READ) {
        verbose(env, "only read from %s is supported\n", tname);
        return -EACCES;
    }

    ret = btf_struct_access(&env->log, t, off, size, atype, &btf_id);
    if (ret < 0) {
        return ret;
    }

    if (value_regno >= 0) {
        mark_btf_ld_reg(env, regs, value_regno, ret, btf_id);
    }

    return 0;
}

/* Check that the stack access at the given offset is within bounds. The
 * maximum valid offset is -1.
 *
 * The minimum valid offset is -MAX_BPF_STACK for writes, and
 * -state->allocated_stack for reads.
 */
static int check_stack_slot_within_bounds(int off, struct bpf_func_state *state, enum bpf_access_type t)
{
    int min_valid_off;

    if (t == BPF_WRITE) {
        min_valid_off = -MAX_BPF_STACK;
    } else {
        min_valid_off = -state->allocated_stack;
    }

    if (off < min_valid_off || off > -1) {
        return -EACCES;
    }
    return 0;
}

/* Check that the stack access at 'regno + off' falls within the maximum stack
 * bounds.
 *
 * 'off' includes `regno->offset`, but not its dynamic part (if any).
 */
static int check_stack_access_within_bounds(struct bpf_verifier_env *env, int regno, int off, int access_size,
                                            enum stack_access_src src, enum bpf_access_type type)
{
    struct bpf_reg_state *regs = cur_regs(env);
    struct bpf_reg_state *reg = regs + regno;
    struct bpf_func_state *state = func(env, reg);
    int min_off, max_off;
    int err;
    char *err_extra;

    if (src == ACCESS_HELPER) {
        /* We don't know if helpers are reading or writing (or both). */
        err_extra = " indirect access to";
    } else if (type == BPF_READ) {
        err_extra = " read from";
    } else {
        err_extra = " write to";
    }

    if (tnum_is_const(reg->var_off)) {
        min_off = reg->var_off.value + off;
        if (access_size > 0) {
            max_off = min_off + access_size - 1;
        } else {
            max_off = min_off;
        }
    } else {
        if (reg->smax_value >= BPF_MAX_VAR_OFF || reg->smin_value <= -BPF_MAX_VAR_OFF) {
            verbose(env, "invalid unbounded variable-offset%s stack R%d\n", err_extra, regno);
            return -EACCES;
        }
        min_off = reg->smin_value + off;
        if (access_size > 0) {
            max_off = reg->smax_value + off + access_size - 1;
        } else {
            max_off = min_off;
        }
    }

    err = check_stack_slot_within_bounds(min_off, state, type);
    if (!err) {
        err = check_stack_slot_within_bounds(max_off, state, type);
    }

    if (err) {
        if (tnum_is_const(reg->var_off)) {
            verbose(env, "invalid%s stack R%d off=%d size=%d\n", err_extra, regno, off, access_size);
        } else {
            char tn_buf[48];

            tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
            verbose(env, "invalid variable-offset%s stack R%d var_off=%s size=%d\n", err_extra, regno, tn_buf,
                    access_size);
        }
    }
    return err;
}

/* check whether memory at (regno + off) is accessible for t = (read | write)
 * if t==write, value_regno is a register which value is stored into memory
 * if t==read, value_regno is a register which will receive the value from memory
 * if t==write && value_regno==-1, some unknown value is stored into memory
 * if t==read && value_regno==-1, don't care what we read from memory
 */
static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno, int off, int bpf_size,
                            enum bpf_access_type t, int value_regno, bool strict_alignment_once)
{
    struct bpf_reg_state *regs = cur_regs(env);
    struct bpf_reg_state *reg = regs + regno;
    struct bpf_func_state *state;
    int size, err = 0;

    size = bpf_size_to_bytes(bpf_size);
    if (size < 0) {
        return size;
    }

    /* alignment checks will add in reg->off themselves */
    err = check_ptr_alignment(env, reg, off, size, strict_alignment_once);
    if (err) {
        return err;
    }

    /* for access checks, reg->off is just part of off */
    off += reg->off;

    if (reg->type == PTR_TO_MAP_VALUE) {
        if (t == BPF_WRITE && value_regno >= 0 && is_pointer_value(env, value_regno)) {
            verbose(env, "R%d leaks addr into map\n", value_regno);
            return -EACCES;
        }
        err = check_map_access_type(env, regno, off, size, t);
        if (err) {
            return err;
        }
        err = check_map_access(env, regno, off, size, false);
        if (!err && t == BPF_READ && value_regno >= 0) {
            struct bpf_map *map = reg->map_ptr;

            /* if map is read-only, track its contents as scalars */
            if (tnum_is_const(reg->var_off) && bpf_map_is_rdonly(map) && map->ops->map_direct_value_addr) {
                int map_off = off + reg->var_off.value;
                u64 val = 0;

                err = bpf_map_direct_read(map, map_off, size, &val);
                if (err) {
                    return err;
                }

                regs[value_regno].type = SCALAR_VALUE;
                verifier_mark_reg_known(&regs[value_regno], val);
            } else {
                mark_reg_unknown(env, regs, value_regno);
            }
        }
    } else if (base_type(reg->type) == PTR_TO_MEM) {
        bool rdonly_mem = type_is_rdonly_mem(reg->type);

        if (type_may_be_null(reg->type)) {
            verbose(env, "R%d invalid mem access '%s'\n", regno, reg_type_str(env, reg->type));
            return -EACCES;
        }

        if (t == BPF_WRITE && rdonly_mem) {
            verbose(env, "R%d cannot write into %s\n", regno, reg_type_str(env, reg->type));
            return -EACCES;
        }

        if (t == BPF_WRITE && value_regno >= 0 && is_pointer_value(env, value_regno)) {
            verbose(env, "R%d leaks addr into mem\n", value_regno);
            return -EACCES;
        }

        err = check_mem_region_access(env, regno, off, size, reg->mem_size, false);
        if (!err && value_regno >= 0 && (t == BPF_READ || rdonly_mem)) {
            mark_reg_unknown(env, regs, value_regno);
        }
    } else if (reg->type == PTR_TO_CTX) {
        enum bpf_reg_type reg_type = SCALAR_VALUE;
        u32 btf_id = 0;

        if (t == BPF_WRITE && value_regno >= 0 && is_pointer_value(env, value_regno)) {
            verbose(env, "R%d leaks addr into ctx\n", value_regno);
            return -EACCES;
        }

        err = check_ptr_off_reg(env, reg, regno);
        if (err < 0) {
            return err;
        }

        err = check_ctx_access(env, insn_idx, off, size, t, &reg_type, &btf_id);
        if (err) {
            verbose_linfo(env, insn_idx, "; ");
        }
        if (!err && t == BPF_READ && value_regno >= 0) {
            /* ctx access returns either a scalar, or a
             * PTR_TO_PACKET[_META,_END]. In the latter
             * case, we know the offset is zero.
             */
            if (reg_type == SCALAR_VALUE) {
                mark_reg_unknown(env, regs, value_regno);
            } else {
                mark_reg_known_zero(env, regs, value_regno);
                if (type_may_be_null(reg_type)) {
                    regs[value_regno].id = ++env->id_gen;
                }
                /* A load of ctx field could have different
                 * actual load size with the one encoded in the
                 * insn. When the dst is PTR, it is for sure not
                 * a sub-register.
                 */
                regs[value_regno].subreg_def = DEF_NOT_SUBREG;
                if (base_type(reg_type) == PTR_TO_BTF_ID) {
                    regs[value_regno].btf_id = btf_id;
                }
            }
            regs[value_regno].type = reg_type;
        }
    } else if (reg->type == PTR_TO_STACK) {
        /* Basic bounds checks. */
        err = check_stack_access_within_bounds(env, regno, off, size, ACCESS_DIRECT, t);
        if (err) {
            return err;
        }
        state = func(env, reg);
        err = update_stack_depth(env, state, off);
        if (err) {
            return err;
        }

        if (t == BPF_READ) {
            err = check_stack_read(env, regno, off, size, value_regno);
        } else {
            err = check_stack_write(env, regno, off, size, value_regno, insn_idx);
        }
    } else if (reg_is_pkt_pointer(reg)) {
        if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) {
            verbose(env, "cannot write into packet\n");
            return -EACCES;
        }
        if (t == BPF_WRITE && value_regno >= 0 && is_pointer_value(env, value_regno)) {
            verbose(env, "R%d leaks addr into packet\n", value_regno);
            return -EACCES;
        }
        err = check_packet_access(env, regno, off, size, false);
        if (!err && t == BPF_READ && value_regno >= 0) {
            mark_reg_unknown(env, regs, value_regno);
        }
    } else if (reg->type == PTR_TO_FLOW_KEYS) {
        if (t == BPF_WRITE && value_regno >= 0 && is_pointer_value(env, value_regno)) {
            verbose(env, "R%d leaks addr into flow keys\n", value_regno);
            return -EACCES;
        }

        err = check_flow_keys_access(env, off, size);
        if (!err && t == BPF_READ && value_regno >= 0) {
            mark_reg_unknown(env, regs, value_regno);
        }
    } else if (type_is_sk_pointer(reg->type)) {
        if (t == BPF_WRITE) {
            verbose(env, "R%d cannot write into %s\n", regno, reg_type_str(env, reg->type));
            return -EACCES;
        }
        err = check_sock_access(env, insn_idx, regno, off, size, t);
        if (!err && value_regno >= 0) {
            mark_reg_unknown(env, regs, value_regno);
        }
    } else if (reg->type == PTR_TO_TP_BUFFER) {
        err = check_tp_buffer_access(env, reg, regno, off, size);
        if (!err && t == BPF_READ && value_regno >= 0) {
            mark_reg_unknown(env, regs, value_regno);
        }
    } else if (reg->type == PTR_TO_BTF_ID) {
        err = check_ptr_to_btf_access(env, regs, regno, off, size, t, value_regno);
    } else if (reg->type == CONST_PTR_TO_MAP) {
        err = check_ptr_to_map_access(env, regs, regno, off, size, t, value_regno);
    } else if (base_type(reg->type) == PTR_TO_BUF) {
        bool rdonly_mem = type_is_rdonly_mem(reg->type);
        const char *buf_info;
        u32 *max_access;

        if (rdonly_mem) {
            if (t == BPF_WRITE) {
                verbose(env, "R%d cannot write into %s\n", regno, reg_type_str(env, reg->type));
                return -EACCES;
            }
            buf_info = "rdonly";
            max_access = &env->prog->aux->max_rdonly_access;
        } else {
            buf_info = "rdwr";
            max_access = &env->prog->aux->max_rdwr_access;
        }

        err = check_buffer_access(env, reg, regno, off, size, false, buf_info, max_access);
        if (!err && value_regno >= 0 && (rdonly_mem || t == BPF_READ)) {
            mark_reg_unknown(env, regs, value_regno);
        }
    } else {
        verbose(env, "R%d invalid mem access '%s'\n", regno, reg_type_str(env, reg->type));
        return -EACCES;
    }

    if (!err && size < BPF_REG_SIZE && value_regno >= 0 && t == BPF_READ && regs[value_regno].type == SCALAR_VALUE) {
        /* b/h/w load zero-extends, mark upper bits as known 0 */
        coerce_reg_to_size(&regs[value_regno], size);
    }
    return err;
}

static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn)
{
    int err;

    if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) || insn->imm != 0) {
        verbose(env, "BPF_XADD uses reserved fields\n");
        return -EINVAL;
    }

    /* check src1 operand */
    err = check_reg_arg(env, insn->src_reg, SRC_OP);
    if (err) {
        return err;
    }

    /* check src2 operand */
    err = check_reg_arg(env, insn->dst_reg, SRC_OP);
    if (err) {
        return err;
    }

    if (is_pointer_value(env, insn->src_reg)) {
        verbose(env, "R%d leaks addr into mem\n", insn->src_reg);
        return -EACCES;
    }

    if (is_ctx_reg(env, insn->dst_reg) || is_pkt_reg(env, insn->dst_reg) || is_flow_key_reg(env, insn->dst_reg) ||
        is_sk_reg(env, insn->dst_reg)) {
        verbose(env, "BPF_XADD stores into R%d %s is not allowed\n", insn->dst_reg,
                reg_type_str(env, reg_state(env, insn->dst_reg)->type));
        return -EACCES;
    }

    /* check whether atomic_add can read the memory */
    err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off, BPF_SIZE(insn->code), BPF_READ, -1, true);
    if (err) {
        return err;
    }

    /* check whether atomic_add can write into the same memory */
    return check_mem_access(env, insn_idx, insn->dst_reg, insn->off, BPF_SIZE(insn->code), BPF_WRITE, -1, true);
}

/* When register 'regno' is used to read the stack (either directly or through
 * a helper function) make sure that it's within stack boundary and, depending
 * on the access type, that all elements of the stack are initialized.
 *
 * 'off' includes 'regno->off', but not its dynamic part (if any).
 *
 * All registers that have been spilled on the stack in the slots within the
 * read offsets are marked as read.
 */
static int check_stack_range_initialized(struct bpf_verifier_env *env, int regno, int off, int access_size,
                                         bool zero_size_allowed, enum stack_access_src type,
                                         struct bpf_call_arg_meta *meta)
{
    struct bpf_reg_state *reg = reg_state(env, regno);
    struct bpf_func_state *state = func(env, reg);
    int err, min_off, max_off, i, j, slot, spi;
    char *err_extra = type == ACCESS_HELPER ? " indirect" : "";
    enum bpf_access_type bounds_check_type;
    /* Some accesses can write anything into the stack, others are
     * read-only.
     */
    bool clobber = false;

    if (access_size == 0 && !zero_size_allowed) {
        verbose(env, "invalid zero-sized read\n");
        return -EACCES;
    }

    if (type == ACCESS_HELPER) {
        /* The bounds checks for writes are more permissive than for
         * reads. However, if raw_mode is not set, we'll do extra
         * checks below.
         */
        bounds_check_type = BPF_WRITE;
        clobber = true;
    } else {
        bounds_check_type = BPF_READ;
    }
    err = check_stack_access_within_bounds(env, regno, off, access_size, type, bounds_check_type);
    if (err) {
        return err;
    }

    if (tnum_is_const(reg->var_off)) {
        min_off = max_off = reg->var_off.value + off;
    } else {
        /* Variable offset is prohibited for unprivileged mode for
         * simplicity since it requires corresponding support in
         * Spectre masking for stack ALU.
         * See also retrieve_ptr_limit().
         */
        if (!env->bypass_spec_v1) {
            char tn_buf[48];

            tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
            verbose(env, "R%d%s variable offset stack access prohibited for !root, var_off=%s\n", regno, err_extra,
                    tn_buf);
            return -EACCES;
        }
        /* Only initialized buffer on stack is allowed to be accessed
         * with variable offset. With uninitialized buffer it's hard to
         * guarantee that whole memory is marked as initialized on
         * helper return since specific bounds are unknown what may
         * cause uninitialized stack leaking.
         */
        if (meta && meta->raw_mode) {
            meta = NULL;
        }

        min_off = reg->smin_value + off;
        max_off = reg->smax_value + off;
    }

    if (meta && meta->raw_mode) {
        meta->access_size = access_size;
        meta->regno = regno;
        return 0;
    }

    for (i = min_off; i < max_off + access_size; i++) {
        u8 *stype;

        slot = -i - 1;
        spi = slot / BPF_REG_SIZE;
        if (state->allocated_stack <= slot) {
            goto err;
        }
        stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];
        if (*stype == STACK_MISC) {
            goto mark;
        }
        if (*stype == STACK_ZERO) {
            if (clobber) {
                /* helper can write anything into the stack */
                *stype = STACK_MISC;
            }
            goto mark;
        }

        if (state->stack[spi].slot_type[0] == STACK_SPILL && state->stack[spi].spilled_ptr.type == PTR_TO_BTF_ID) {
            goto mark;
        }

        if (state->stack[spi].slot_type[0] == STACK_SPILL &&
            (state->stack[spi].spilled_ptr.type == SCALAR_VALUE || env->allow_ptr_leaks)) {
            if (clobber) {
                __mark_reg_unknown(env, &state->stack[spi].spilled_ptr);
                for (j = 0; j < BPF_REG_SIZE; j++) {
                    state->stack[spi].slot_type[j] = STACK_MISC;
                }
            }
            goto mark;
        }

    err:
        if (tnum_is_const(reg->var_off)) {
            verbose(env, "invalid%s read from stack R%d off %d+%d size %d\n", err_extra, regno, min_off, i - min_off,
                    access_size);
        } else {
            char tn_buf[48];

            tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
            verbose(env, "invalid%s read from stack R%d var_off %s+%d size %d\n", err_extra, regno, tn_buf, i - min_off,
                    access_size);
        }
        return -EACCES;
    mark:
        /* reading any byte out of 8-byte 'spill_slot' will cause
         * the whole slot to be marked as 'read'
         */
        mark_reg_read(env, &state->stack[spi].spilled_ptr, state->stack[spi].spilled_ptr.parent, REG_LIVE_READ64);
    }
    return update_stack_depth(env, state, min_off);
}

static int check_helper_mem_access(struct bpf_verifier_env *env, int regno, int access_size, bool zero_size_allowed,
                                   struct bpf_call_arg_meta *meta)
{
    struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
    const char *buf_info;
    u32 *max_access;

    switch (base_type(reg->type)) {
        case PTR_TO_PACKET:
        case PTR_TO_PACKET_META:
            return check_packet_access(env, regno, reg->off, access_size, zero_size_allowed);
        case PTR_TO_MAP_VALUE:
            if (check_map_access_type(env, regno, reg->off, access_size,
                                      meta && meta->raw_mode ? BPF_WRITE : BPF_READ)) {
                return -EACCES;
            }
            return check_map_access(env, regno, reg->off, access_size, zero_size_allowed);
        case PTR_TO_MEM:
            return check_mem_region_access(env, regno, reg->off, access_size, reg->mem_size, zero_size_allowed);
        case PTR_TO_BUF:
            if (type_is_rdonly_mem(reg->type)) {
                if (meta && meta->raw_mode) {
                    return -EACCES;
                }

                buf_info = "rdonly";
                max_access = &env->prog->aux->max_rdonly_access;
            } else {
                buf_info = "rdwr";
                max_access = &env->prog->aux->max_rdwr_access;
            }
            return check_buffer_access(env, reg, regno, reg->off, access_size, zero_size_allowed, buf_info, max_access);
        case PTR_TO_STACK:
            return check_stack_range_initialized(env, regno, reg->off, access_size, zero_size_allowed, ACCESS_HELPER,
                                                 meta);
        default: /* scalar_value or invalid ptr */
            /* Allow zero-byte read from NULL, regardless of pointer type */
            if (zero_size_allowed && access_size == 0 && register_is_null(reg)) {
                return 0;
            }

            verbose(env, "R%d type=%s ", regno, reg_type_str(env, reg->type));
            verbose(env, "expected=%s\n", reg_type_str(env, PTR_TO_STACK));
            return -EACCES;
    }
}

/* Implementation details:
 * bpf_map_lookup returns PTR_TO_MAP_VALUE_OR_NULL
 * Two bpf_map_lookups (even with the same key) will have different reg->id.
 * For traditional PTR_TO_MAP_VALUE the verifier clears reg->id after
 * value_or_null->value transition, since the verifier only cares about
 * the range of access to valid map value pointer and doesn't care about actual
 * address of the map element.
 * For maps with 'struct bpf_spin_lock' inside map value the verifier keeps
 * reg->id > 0 after value_or_null->value transition. By doing so
 * two bpf_map_lookups will be considered two different pointers that
 * point to different bpf_spin_locks.
 * The verifier allows taking only one bpf_spin_lock at a time to avoid
 * dead-locks.
 * Since only one bpf_spin_lock is allowed the checks are simpler than
 * reg_is_refcounted() logic. The verifier needs to remember only
 * one spin_lock instead of array of acquired_refs.
 * cur_state->active_spin_lock remembers which map value element got locked
 * and clears it after bpf_spin_unlock.
 */
static int process_spin_lock(struct bpf_verifier_env *env, int regno, bool is_lock)
{
    struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
    struct bpf_verifier_state *cur = env->cur_state;
    bool is_const = tnum_is_const(reg->var_off);
    struct bpf_map *map = reg->map_ptr;
    u64 val = reg->var_off.value;

    if (!is_const) {
        verbose(env, "R%d doesn't have constant offset. bpf_spin_lock has to be at the constant offset\n", regno);
        return -EINVAL;
    }
    if (!map->btf) {
        verbose(env, "map '%s' has to have BTF in order to use bpf_spin_lock\n", map->name);
        return -EINVAL;
    }
    if (!map_value_has_spin_lock(map)) {
        if (map->spin_lock_off == -E2BIG) {
            verbose(env, "map '%s' has more than one 'struct bpf_spin_lock'\n", map->name);
        } else if (map->spin_lock_off == -ENOENT) {
            verbose(env, "map '%s' doesn't have 'struct bpf_spin_lock'\n", map->name);
        } else {
            verbose(env, "map '%s' is not a struct type or bpf_spin_lock is mangled\n", map->name);
        }
        return -EINVAL;
    }
    if (map->spin_lock_off != val + reg->off) {
        verbose(env, "off %lld doesn't point to 'struct bpf_spin_lock'\n", val + reg->off);
        return -EINVAL;
    }
    if (is_lock) {
        if (cur->active_spin_lock) {
            verbose(env, "Locking two bpf_spin_locks are not allowed\n");
            return -EINVAL;
        }
        cur->active_spin_lock = reg->id;
    } else {
        if (!cur->active_spin_lock) {
            verbose(env, "bpf_spin_unlock without taking a lock\n");
            return -EINVAL;
        }
        if (cur->active_spin_lock != reg->id) {
            verbose(env, "bpf_spin_unlock of different lock\n");
            return -EINVAL;
        }
        cur->active_spin_lock = 0;
    }
    return 0;
}

static bool arg_type_is_mem_ptr(enum bpf_arg_type type)
{
    return base_type(type) == ARG_PTR_TO_MEM || base_type(type) == ARG_PTR_TO_UNINIT_MEM;
}

static bool arg_type_is_mem_size(enum bpf_arg_type type)
{
    return type == ARG_CONST_SIZE || type == ARG_CONST_SIZE_OR_ZERO;
}

static bool arg_type_is_alloc_size(enum bpf_arg_type type)
{
    return type == ARG_CONST_ALLOC_SIZE_OR_ZERO;
}

static bool arg_type_is_int_ptr(enum bpf_arg_type type)
{
    return type == ARG_PTR_TO_INT || type == ARG_PTR_TO_LONG;
}

static int int_ptr_type_to_size(enum bpf_arg_type type)
{
    if (type == ARG_PTR_TO_INT) {
        return sizeof(u32);
    } else if (type == ARG_PTR_TO_LONG) {
        return sizeof(u64);
    }

    return -EINVAL;
}

static int resolve_map_arg_type(struct bpf_verifier_env *env, const struct bpf_call_arg_meta *meta,
                                enum bpf_arg_type *arg_type)
{
    if (!meta->map_ptr) {
        /* kernel subsystem misconfigured verifier */
        verbose(env, "invalid map_ptr to access map->type\n");
        return -EACCES;
    }

    switch (meta->map_ptr->map_type) {
        case BPF_MAP_TYPE_SOCKMAP:
        case BPF_MAP_TYPE_SOCKHASH:
            if (*arg_type == ARG_PTR_TO_MAP_VALUE) {
                *arg_type = ARG_PTR_TO_BTF_ID_SOCK_COMMON;
            } else {
                verbose(env, "invalid arg_type for sockmap/sockhash\n");
                return -EINVAL;
            }
            break;

        default:
            break;
    }
    return 0;
}

struct bpf_reg_types {
    const enum bpf_reg_type types[10];
    u32 *btf_id;
};

static const struct bpf_reg_types map_key_value_types = {
    .types =
        {
            PTR_TO_STACK,
            PTR_TO_PACKET,
            PTR_TO_PACKET_META,
            PTR_TO_MAP_VALUE,
        },
};

static const struct bpf_reg_types sock_types = {
    .types =
        {
            PTR_TO_SOCK_COMMON,
            PTR_TO_SOCKET,
            PTR_TO_TCP_SOCK,
            PTR_TO_XDP_SOCK,
        },
};

#ifdef CONFIG_NET
static const struct bpf_reg_types btf_id_sock_common_types = {
    .types =
        {
            PTR_TO_SOCK_COMMON,
            PTR_TO_SOCKET,
            PTR_TO_TCP_SOCK,
            PTR_TO_XDP_SOCK,
            PTR_TO_BTF_ID,
        },
    .btf_id = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
};
#endif

static const struct bpf_reg_types mem_types = {
    .types =
        {
            PTR_TO_STACK,
            PTR_TO_PACKET,
            PTR_TO_PACKET_META,
            PTR_TO_MAP_VALUE,
            PTR_TO_MEM,
            PTR_TO_MEM | MEM_ALLOC,
            PTR_TO_BUF,
        },
};

static const struct bpf_reg_types int_ptr_types = {
    .types =
        {
            PTR_TO_STACK,
            PTR_TO_PACKET,
            PTR_TO_PACKET_META,
            PTR_TO_MAP_VALUE,
        },
};

static const struct bpf_reg_types fullsock_types = {.types = {PTR_TO_SOCKET}};
static const struct bpf_reg_types scalar_types = {.types = {SCALAR_VALUE}};
static const struct bpf_reg_types context_types = {.types = {PTR_TO_CTX}};
static const struct bpf_reg_types alloc_mem_types = {.types = {PTR_TO_MEM | MEM_ALLOC}};
static const struct bpf_reg_types const_map_ptr_types = {.types = {CONST_PTR_TO_MAP}};
static const struct bpf_reg_types btf_ptr_types = {.types = {PTR_TO_BTF_ID}};
static const struct bpf_reg_types spin_lock_types = {.types = {PTR_TO_MAP_VALUE}};
static const struct bpf_reg_types percpu_btf_ptr_types = {.types = {PTR_TO_PERCPU_BTF_ID}};

static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
    [ARG_PTR_TO_MAP_KEY] = &map_key_value_types,
    [ARG_PTR_TO_MAP_VALUE] = &map_key_value_types,
    [ARG_PTR_TO_UNINIT_MAP_VALUE] = &map_key_value_types,
    [ARG_CONST_SIZE] = &scalar_types,
    [ARG_CONST_SIZE_OR_ZERO] = &scalar_types,
    [ARG_CONST_ALLOC_SIZE_OR_ZERO] = &scalar_types,
    [ARG_CONST_MAP_PTR] = &const_map_ptr_types,
    [ARG_PTR_TO_CTX] = &context_types,
    [ARG_PTR_TO_SOCK_COMMON] = &sock_types,
#ifdef CONFIG_NET
    [ARG_PTR_TO_BTF_ID_SOCK_COMMON] = &btf_id_sock_common_types,
#endif
    [ARG_PTR_TO_SOCKET] = &fullsock_types,
    [ARG_PTR_TO_BTF_ID] = &btf_ptr_types,
    [ARG_PTR_TO_SPIN_LOCK] = &spin_lock_types,
    [ARG_PTR_TO_MEM] = &mem_types,
    [ARG_PTR_TO_UNINIT_MEM] = &mem_types,
    [ARG_PTR_TO_ALLOC_MEM] = &alloc_mem_types,
    [ARG_PTR_TO_INT] = &int_ptr_types,
    [ARG_PTR_TO_LONG] = &int_ptr_types,
    [ARG_PTR_TO_PERCPU_BTF_ID] = &percpu_btf_ptr_types,
};

static int check_reg_type(struct bpf_verifier_env *env, u32 regno, enum bpf_arg_type arg_type, const u32 *arg_btf_id)
{
    struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
    enum bpf_reg_type expected, type = reg->type;
    const struct bpf_reg_types *compatible;
    int i, j;

    compatible = compatible_reg_types[base_type(arg_type)];
    if (!compatible) {
        verbose(env, "verifier internal error: unsupported arg type %d\n", arg_type);
        return -EFAULT;
    }

    /* ARG_PTR_TO_MEM + RDONLY is compatible with PTR_TO_MEM and PTR_TO_MEM + RDONLY,
     * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM and NOT with PTR_TO_MEM + RDONLY
     *
     * Same for MAYBE_NULL:
     *
     * ARG_PTR_TO_MEM + MAYBE_NULL is compatible with PTR_TO_MEM and PTR_TO_MEM + MAYBE_NULL,
     * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM but NOT with PTR_TO_MEM + MAYBE_NULL
     *
     * Therefore we fold these flags depending on the arg_type before comparison.
     */
    if (arg_type & MEM_RDONLY) {
        type &= ~MEM_RDONLY;
    }
    if (arg_type & PTR_MAYBE_NULL) {
        type &= ~PTR_MAYBE_NULL;
    }

    for (i = 0; i < ARRAY_SIZE(compatible->types); i++) {
        expected = compatible->types[i];
        if (expected == NOT_INIT) {
            break;
        }

        if (type == expected) {
            goto found;
        }
    }

    verbose(env, "R%d type=%s expected=", regno, reg_type_str(env, reg->type));
    for (j = 0; j + 1 < i; j++) {
        verbose(env, "%s, ", reg_type_str(env, compatible->types[j]));
    }
    verbose(env, "%s\n", reg_type_str(env, compatible->types[j]));
    return -EACCES;

found:
    if (reg->type == PTR_TO_BTF_ID) {
        if (!arg_btf_id) {
            if (!compatible->btf_id) {
                verbose(env, "verifier internal error: missing arg compatible BTF ID\n");
                return -EFAULT;
            }
            arg_btf_id = compatible->btf_id;
        }

        if (!btf_struct_ids_match(&env->log, reg->off, reg->btf_id, *arg_btf_id)) {
            verbose(env, "R%d is of type %s but %s is expected\n", regno, kernel_type_name(reg->btf_id),
                    kernel_type_name(*arg_btf_id));
            return -EACCES;
        }
    }

    return 0;
}

static int check_func_arg(struct bpf_verifier_env *env, u32 arg, struct bpf_call_arg_meta *meta,
                          const struct bpf_func_proto *fn)
{
    u32 regno = BPF_REG_1 + arg;
    struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
    enum bpf_arg_type arg_type = fn->arg_type[arg];
    enum bpf_reg_type type = reg->type;
    int err = 0;

    if (arg_type == ARG_DONTCARE) {
        return 0;
    }

    err = check_reg_arg(env, regno, SRC_OP);
    if (err) {
        return err;
    }

    if (arg_type == ARG_ANYTHING) {
        if (is_pointer_value(env, regno)) {
            verbose(env, "R%d leaks addr into helper function\n", regno);
            return -EACCES;
        }
        return 0;
    }

    if (type_is_pkt_pointer(type) && !may_access_direct_pkt_data(env, meta, BPF_READ)) {
        verbose(env, "helper access to the packet is not allowed\n");
        return -EACCES;
    }

    if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE || base_type(arg_type) == ARG_PTR_TO_UNINIT_MAP_VALUE) {
        err = resolve_map_arg_type(env, meta, &arg_type);
        if (err) {
            return err;
        }
    }

    if (register_is_null(reg) && type_may_be_null(arg_type)) {
        /* A NULL register has a SCALAR_VALUE type, so skip
         * type checking.
         */
        goto skip_type_check;
    }

    err = check_reg_type(env, regno, arg_type, fn->arg_btf_id[arg]);
    if (err) {
        return err;
    }

    switch ((u32)type) {
        case SCALAR_VALUE:
        /* Pointer types where reg offset is explicitly allowed: */
        case PTR_TO_PACKET:
        case PTR_TO_PACKET_META:
        case PTR_TO_MAP_VALUE:
        case PTR_TO_MEM:
        case PTR_TO_MEM | MEM_RDONLY:
        case PTR_TO_MEM | MEM_ALLOC:
        case PTR_TO_BUF:
        case PTR_TO_BUF | MEM_RDONLY:
        case PTR_TO_STACK:
            /* Some of the argument types nevertheless require a
             * zero register offset.
             */
            if (arg_type == ARG_PTR_TO_ALLOC_MEM) {
                goto force_off_check;
            }
            break;
        /* All the rest must be rejected: */
        default:
            force_off_check:
            err = __check_ptr_off_reg(env, reg, regno, type == PTR_TO_BTF_ID);
            if (err < 0) {
                return err;
            }
            break;
    }

skip_type_check:
    if (reg->ref_obj_id) {
        if (meta->ref_obj_id) {
            verbose(env, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n", regno,
                    reg->ref_obj_id, meta->ref_obj_id);
            return -EFAULT;
        }
        meta->ref_obj_id = reg->ref_obj_id;
    }

    if (arg_type == ARG_CONST_MAP_PTR) {
        /* bpf_map_xxx(map_ptr) call: remember that map_ptr */
        meta->map_ptr = reg->map_ptr;
    } else if (arg_type == ARG_PTR_TO_MAP_KEY) {
        /* bpf_map_xxx(..., map_ptr, ..., key) call:
         * check that [key, key + map->key_size) are within
         * stack limits and initialized
         */
        if (!meta->map_ptr) {
            /* in function declaration map_ptr must come before
             * map_key, so that it's verified and known before
             * we have to check map_key here. Otherwise it means
             * that kernel subsystem misconfigured verifier
             */
            verbose(env, "invalid map_ptr to access map->key\n");
            return -EACCES;
        }
        err = check_helper_mem_access(env, regno, meta->map_ptr->key_size, false, NULL);
    } else if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE || base_type(arg_type) == ARG_PTR_TO_UNINIT_MAP_VALUE) {
        if (type_may_be_null(arg_type) && register_is_null(reg)) {
            return 0;
        }

        /* bpf_map_xxx(..., map_ptr, ..., value) call:
         * check [value, value + map->value_size) validity
         */
        if (!meta->map_ptr) {
            /* kernel subsystem misconfigured verifier */
            verbose(env, "invalid map_ptr to access map->value\n");
            return -EACCES;
        }
        meta->raw_mode = (arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE);
        err = check_helper_mem_access(env, regno, meta->map_ptr->value_size, false, meta);
    } else if (arg_type == ARG_PTR_TO_PERCPU_BTF_ID) {
        if (!reg->btf_id) {
            verbose(env, "Helper has invalid btf_id in R%d\n", regno);
            return -EACCES;
        }
        meta->ret_btf_id = reg->btf_id;
    } else if (arg_type == ARG_PTR_TO_SPIN_LOCK) {
        if (meta->func_id == BPF_FUNC_spin_lock) {
            if (process_spin_lock(env, regno, true)) {
                return -EACCES;
            }
        } else if (meta->func_id == BPF_FUNC_spin_unlock) {
            if (process_spin_lock(env, regno, false)) {
                return -EACCES;
            }
        } else {
            verbose(env, "verifier internal error\n");
            return -EFAULT;
        }
    } else if (arg_type_is_mem_ptr(arg_type)) {
        /* The access to this pointer is only checked when we hit the
         * next is_mem_size argument below.
         */
        meta->raw_mode = (arg_type == ARG_PTR_TO_UNINIT_MEM);
    } else if (arg_type_is_mem_size(arg_type)) {
        bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO);

        /* This is used to refine r0 return value bounds for helpers
         * that enforce this value as an upper bound on return values.
         * See do_refine_retval_range() for helpers that can refine
         * the return value. C type of helper is u32 so we pull register
         * bound from umax_value however, if negative verifier errors
         * out. Only upper bounds can be learned because retval is an
         * int type and negative retvals are allowed.
         */
        meta->msize_max_value = reg->umax_value;

        /* The register is SCALAR_VALUE; the access check
         * happens using its boundaries.
         */
        if (!tnum_is_const(reg->var_off)) {
            /* For unprivileged variable accesses, disable raw
             * mode so that the program is required to
             * initialize all the memory that the helper could
             * just partially fill up.
             */
            meta = NULL;
        }

        if (reg->smin_value < 0) {
            verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n", regno);
            return -EACCES;
        }

        if (reg->umin_value == 0) {
            err = check_helper_mem_access(env, regno - 1, 0, zero_size_allowed, meta);
            if (err) {
                return err;
            }
        }

        if (reg->umax_value >= BPF_MAX_VAR_SIZ) {
            verbose(env, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n", regno);
            return -EACCES;
        }
        err = check_helper_mem_access(env, regno - 1, reg->umax_value, zero_size_allowed, meta);
        if (!err) {
            err = mark_chain_precision(env, regno);
        }
    } else if (arg_type_is_alloc_size(arg_type)) {
        if (!tnum_is_const(reg->var_off)) {
            verbose(env, "R%d unbounded size, use 'var &= const' or 'if (var < const)'\n", regno);
            return -EACCES;
        }
        meta->mem_size = reg->var_off.value;
    } else if (arg_type_is_int_ptr(arg_type)) {
        int size = int_ptr_type_to_size(arg_type);

        err = check_helper_mem_access(env, regno, size, false, meta);
        if (err) {
            return err;
        }
        err = check_ptr_alignment(env, reg, 0, size, true);
    }

    return err;
}

static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id)
{
    enum bpf_attach_type eatype = env->prog->expected_attach_type;
    enum bpf_prog_type type = resolve_prog_type(env->prog);

    if (func_id != BPF_FUNC_map_update_elem) {
        return false;
    }

    /* It's not possible to get access to a locked struct sock in these
     * contexts, so updating is safe.
     */
    switch (type) {
        case BPF_PROG_TYPE_TRACING:
            if (eatype == BPF_TRACE_ITER) {
                return true;
            }
            break;
        case BPF_PROG_TYPE_SOCKET_FILTER:
        case BPF_PROG_TYPE_SCHED_CLS:
        case BPF_PROG_TYPE_SCHED_ACT:
        case BPF_PROG_TYPE_XDP:
        case BPF_PROG_TYPE_SK_REUSEPORT:
        case BPF_PROG_TYPE_FLOW_DISSECTOR:
        case BPF_PROG_TYPE_SK_LOOKUP:
            return true;
        default:
            break;
    }

    verbose(env, "cannot update sockmap in this context\n");
    return false;
}

static bool allow_tail_call_in_subprogs(struct bpf_verifier_env *env)
{
    return env->prog->jit_requested && IS_ENABLED(CONFIG_X86_64);
}

static int check_map_func_compatibility(struct bpf_verifier_env *env, struct bpf_map *map, int func_id)
{
    if (!map) {
        return 0;
    }

    /* We need a two way check, first is from map perspective ... */
    switch (map->map_type) {
        case BPF_MAP_TYPE_PROG_ARRAY:
            if (func_id != BPF_FUNC_tail_call) {
                goto error;
            }
            break;
        case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
            if (func_id != BPF_FUNC_perf_event_read && func_id != BPF_FUNC_perf_event_output &&
                func_id != BPF_FUNC_skb_output && func_id != BPF_FUNC_perf_event_read_value &&
                func_id != BPF_FUNC_xdp_output) {
                goto error;
            }
            break;
        case BPF_MAP_TYPE_RINGBUF:
            if (func_id != BPF_FUNC_ringbuf_output && func_id != BPF_FUNC_ringbuf_reserve &&
                func_id != BPF_FUNC_ringbuf_query) {
                goto error;
            }
            break;
        case BPF_MAP_TYPE_STACK_TRACE:
            if (func_id != BPF_FUNC_get_stackid) {
                goto error;
            }
            break;
        case BPF_MAP_TYPE_CGROUP_ARRAY:
            if (func_id != BPF_FUNC_skb_under_cgroup && func_id != BPF_FUNC_current_task_under_cgroup) {
                goto error;
            }
            break;
        case BPF_MAP_TYPE_CGROUP_STORAGE:
        case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
            if (func_id != BPF_FUNC_get_local_storage) {
                goto error;
            }
            break;
        case BPF_MAP_TYPE_DEVMAP:
        case BPF_MAP_TYPE_DEVMAP_HASH:
            if (func_id != BPF_FUNC_redirect_map && func_id != BPF_FUNC_map_lookup_elem) {
                goto error;
            }
            break;
        /* Restrict bpf side of cpumap and xskmap, open when use-cases
         * appear.
         */
        case BPF_MAP_TYPE_CPUMAP:
            if (func_id != BPF_FUNC_redirect_map) {
                goto error;
            }
            break;
        case BPF_MAP_TYPE_XSKMAP:
            if (func_id != BPF_FUNC_redirect_map && func_id != BPF_FUNC_map_lookup_elem) {
                goto error;
            }
            break;
        case BPF_MAP_TYPE_ARRAY_OF_MAPS:
        case BPF_MAP_TYPE_HASH_OF_MAPS:
            if (func_id != BPF_FUNC_map_lookup_elem) {
                goto error;
            }
            break;
        case BPF_MAP_TYPE_SOCKMAP:
            if (func_id != BPF_FUNC_sk_redirect_map && func_id != BPF_FUNC_sock_map_update &&
                func_id != BPF_FUNC_map_delete_elem && func_id != BPF_FUNC_msg_redirect_map &&
                func_id != BPF_FUNC_sk_select_reuseport && func_id != BPF_FUNC_map_lookup_elem &&
                !may_update_sockmap(env, func_id)) {
                goto error;
            }
            break;
        case BPF_MAP_TYPE_SOCKHASH:
            if (func_id != BPF_FUNC_sk_redirect_hash && func_id != BPF_FUNC_sock_hash_update &&
                func_id != BPF_FUNC_map_delete_elem && func_id != BPF_FUNC_msg_redirect_hash &&
                func_id != BPF_FUNC_sk_select_reuseport && func_id != BPF_FUNC_map_lookup_elem &&
                !may_update_sockmap(env, func_id)) {
                goto error;
            }
            break;
        case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
            if (func_id != BPF_FUNC_sk_select_reuseport) {
                goto error;
            }
            break;
        case BPF_MAP_TYPE_QUEUE:
        case BPF_MAP_TYPE_STACK:
            if (func_id != BPF_FUNC_map_peek_elem && func_id != BPF_FUNC_map_pop_elem &&
                func_id != BPF_FUNC_map_push_elem) {
                goto error;
            }
            break;
        case BPF_MAP_TYPE_SK_STORAGE:
            if (func_id != BPF_FUNC_sk_storage_get && func_id != BPF_FUNC_sk_storage_delete) {
                goto error;
            }
            break;
        case BPF_MAP_TYPE_INODE_STORAGE:
            if (func_id != BPF_FUNC_inode_storage_get && func_id != BPF_FUNC_inode_storage_delete) {
                goto error;
            }
            break;
        default:
            break;
    }

    /* ... and second from the function itself. */
    switch (func_id) {
        case BPF_FUNC_tail_call:
            if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY) {
                goto error;
            }
            if (env->subprog_cnt > 1 && !allow_tail_call_in_subprogs(env)) {
                verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n");
                return -EINVAL;
            }
            break;
        case BPF_FUNC_perf_event_read:
        case BPF_FUNC_perf_event_output:
        case BPF_FUNC_perf_event_read_value:
        case BPF_FUNC_skb_output:
        case BPF_FUNC_xdp_output:
            if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) {
                goto error;
            }
            break;
        case BPF_FUNC_ringbuf_output:
        case BPF_FUNC_ringbuf_reserve:
        case BPF_FUNC_ringbuf_query:
            if (map->map_type != BPF_MAP_TYPE_RINGBUF) {
                goto error;
            }
            break;
        case BPF_FUNC_get_stackid:
            if (map->map_type != BPF_MAP_TYPE_STACK_TRACE) {
                goto error;
            }
            break;
        case BPF_FUNC_current_task_under_cgroup:
        case BPF_FUNC_skb_under_cgroup:
            if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY) {
                goto error;
            }
            break;
        case BPF_FUNC_redirect_map:
            if (map->map_type != BPF_MAP_TYPE_DEVMAP && map->map_type != BPF_MAP_TYPE_DEVMAP_HASH &&
                map->map_type != BPF_MAP_TYPE_CPUMAP && map->map_type != BPF_MAP_TYPE_XSKMAP) {
                goto error;
            }
            break;
        case BPF_FUNC_sk_redirect_map:
        case BPF_FUNC_msg_redirect_map:
        case BPF_FUNC_sock_map_update:
            if (map->map_type != BPF_MAP_TYPE_SOCKMAP) {
                goto error;
            }
            break;
        case BPF_FUNC_sk_redirect_hash:
        case BPF_FUNC_msg_redirect_hash:
        case BPF_FUNC_sock_hash_update:
            if (map->map_type != BPF_MAP_TYPE_SOCKHASH) {
                goto error;
            }
            break;
        case BPF_FUNC_get_local_storage:
            if (map->map_type != BPF_MAP_TYPE_CGROUP_STORAGE && map->map_type != BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE) {
                goto error;
            }
            break;
        case BPF_FUNC_sk_select_reuseport:
            if (map->map_type != BPF_MAP_TYPE_REUSEPORT_SOCKARRAY && map->map_type != BPF_MAP_TYPE_SOCKMAP &&
                map->map_type != BPF_MAP_TYPE_SOCKHASH) {
                goto error;
            }
            break;
        case BPF_FUNC_map_peek_elem:
        case BPF_FUNC_map_pop_elem:
        case BPF_FUNC_map_push_elem:
            if (map->map_type != BPF_MAP_TYPE_QUEUE && map->map_type != BPF_MAP_TYPE_STACK) {
                goto error;
            }
            break;
        case BPF_FUNC_sk_storage_get:
        case BPF_FUNC_sk_storage_delete:
            if (map->map_type != BPF_MAP_TYPE_SK_STORAGE) {
                goto error;
            }
            break;
        case BPF_FUNC_inode_storage_get:
        case BPF_FUNC_inode_storage_delete:
            if (map->map_type != BPF_MAP_TYPE_INODE_STORAGE) {
                goto error;
            }
            break;
        default:
            break;
    }

    return 0;
error:
    verbose(env, "cannot pass map_type %d into func %s#%d\n", map->map_type, func_id_name(func_id), func_id);
    return -EINVAL;
}

static bool check_raw_mode_ok(const struct bpf_func_proto *fn)
{
    int count = 0;

    if (fn->arg1_type == ARG_PTR_TO_UNINIT_MEM) {
        count++;
    }
    if (fn->arg2_type == ARG_PTR_TO_UNINIT_MEM) {
        count++;
    }
    if (fn->arg3_type == ARG_PTR_TO_UNINIT_MEM) {
        count++;
    }
    if (fn->arg4_type == ARG_PTR_TO_UNINIT_MEM) {
        count++;
    }
    if (fn->arg5_type == ARG_PTR_TO_UNINIT_MEM) {
        count++;
    }

    /* We only support one arg being in raw mode at the moment,
     * which is sufficient for the helper functions we have
     * right now.
     */
    return count <= 1;
}

static bool check_args_pair_invalid(enum bpf_arg_type arg_curr, enum bpf_arg_type arg_next)
{
    return (arg_type_is_mem_ptr(arg_curr) && !arg_type_is_mem_size(arg_next)) ||
           (!arg_type_is_mem_ptr(arg_curr) && arg_type_is_mem_size(arg_next));
}

static bool check_arg_pair_ok(const struct bpf_func_proto *fn)
{
    /* bpf_xxx(..., buf, len) call will access 'len'
     * bytes from memory 'buf'. Both arg types need
     * to be paired, so make sure there's no buggy
     * helper function specification.
     */
    if (arg_type_is_mem_size(fn->arg1_type) || arg_type_is_mem_ptr(fn->arg5_type) ||
        check_args_pair_invalid(fn->arg1_type, fn->arg2_type) ||
        check_args_pair_invalid(fn->arg2_type, fn->arg3_type) ||
        check_args_pair_invalid(fn->arg3_type, fn->arg4_type) ||
        check_args_pair_invalid(fn->arg4_type, fn->arg5_type)) {
        return false;
    }

    return true;
}

static bool check_refcount_ok(const struct bpf_func_proto *fn, int func_id)
{
    int count = 0;

    if (arg_type_may_be_refcounted(fn->arg1_type)) {
        count++;
    }
    if (arg_type_may_be_refcounted(fn->arg2_type)) {
        count++;
    }
    if (arg_type_may_be_refcounted(fn->arg3_type)) {
        count++;
    }
    if (arg_type_may_be_refcounted(fn->arg4_type)) {
        count++;
    }
    if (arg_type_may_be_refcounted(fn->arg5_type)) {
        count++;
    }

    /* A reference acquiring function cannot acquire
     * another refcounted ptr.
     */
    if (may_be_acquire_function(func_id) && count) {
        return false;
    }

    /* We only support one arg being unreferenced at the moment,
     * which is sufficient for the helper functions we have right now.
     */
    return count <= 1;
}

static bool check_btf_id_ok(const struct bpf_func_proto *fn)
{
    int i;

    for (i = 0; i < ARRAY_SIZE(fn->arg_type); i++) {
        if (fn->arg_type[i] == ARG_PTR_TO_BTF_ID && !fn->arg_btf_id[i]) {
            return false;
        }

        if (fn->arg_type[i] != ARG_PTR_TO_BTF_ID && fn->arg_btf_id[i]) {
            return false;
        }
    }

    return true;
}

static int check_func_proto(const struct bpf_func_proto *fn, int func_id)
{
    return check_raw_mode_ok(fn) && check_arg_pair_ok(fn) && check_btf_id_ok(fn) && check_refcount_ok(fn, func_id)
               ? 0
               : -EINVAL;
}

/* Packet data might have moved, any old PTR_TO_PACKET[_META,_END]
 * are now invalid, so turn them into unknown SCALAR_VALUE.
 */
static void __clear_all_pkt_pointers(struct bpf_verifier_env *env, struct bpf_func_state *state)
{
    struct bpf_reg_state *regs = state->regs, *reg;
    int i;

    for (i = 0; i < MAX_BPF_REG; i++) {
        if (reg_is_pkt_pointer_any(&regs[i])) {
            mark_reg_unknown(env, regs, i);
        }
    }

    bpf_for_each_spilled_reg(i, state, reg)
    {
        if (!reg) {
            continue;
        }
        if (reg_is_pkt_pointer_any(reg)) {
            __mark_reg_unknown(env, reg);
        }
    }
}

static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
{
    struct bpf_verifier_state *vstate = env->cur_state;
    int i;

    for (i = 0; i <= vstate->curframe; i++) {
        __clear_all_pkt_pointers(env, vstate->frame[i]);
    }
}

static void release_reg_references(struct bpf_verifier_env *env, struct bpf_func_state *state, int ref_obj_id)
{
    struct bpf_reg_state *regs = state->regs, *reg;
    int i;

    for (i = 0; i < MAX_BPF_REG; i++) {
        if (regs[i].ref_obj_id == ref_obj_id) {
            mark_reg_unknown(env, regs, i);
        }
    }

    bpf_for_each_spilled_reg(i, state, reg)
    {
        if (!reg) {
            continue;
        }
        if (reg->ref_obj_id == ref_obj_id) {
            __mark_reg_unknown(env, reg);
        }
    }
}

/* The pointer with the specified id has released its reference to kernel
 * resources. Identify all copies of the same pointer and clear the reference.
 */
static int release_reference(struct bpf_verifier_env *env, int ref_obj_id)
{
    struct bpf_verifier_state *vstate = env->cur_state;
    int err;
    int i;

    err = release_reference_state(cur_func(env), ref_obj_id);
    if (err) {
        return err;
    }

    for (i = 0; i <= vstate->curframe; i++) {
        release_reg_references(env, vstate->frame[i], ref_obj_id);
    }

    return 0;
}

static void clear_caller_saved_regs(struct bpf_verifier_env *env, struct bpf_reg_state *regs)
{
    int i;

    /* after the call registers r0 - r5 were scratched */
    for (i = 0; i < CALLER_SAVED_REGS; i++) {
        mark_reg_not_init(env, regs, caller_saved[i]);
        check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
    }
}

static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, int *insn_idx)
{
    struct bpf_verifier_state *state = env->cur_state;
    struct bpf_func_info_aux *func_info_aux;
    struct bpf_func_state *caller, *callee;
    int i, err, subprog, target_insn;
    bool is_global = false;

    if (state->curframe + 1 >= MAX_CALL_FRAMES) {
        verbose(env, "the call stack of %d frames is too deep\n", state->curframe + 2);
        return -E2BIG;
    }

    target_insn = *insn_idx + insn->imm;
    subprog = find_subprog(env, target_insn + 1);
    if (subprog < 0) {
        verbose(env, "verifier bug. No program starts at insn %d\n", target_insn + 1);
        return -EFAULT;
    }

    caller = state->frame[state->curframe];
    if (state->frame[state->curframe + 1]) {
        verbose(env, "verifier bug. Frame %d already allocated\n", state->curframe + 1);
        return -EFAULT;
    }

    func_info_aux = env->prog->aux->func_info_aux;
    if (func_info_aux) {
        is_global = func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL;
    }
    err = btf_check_func_arg_match(env, subprog, caller->regs);
    if (err == -EFAULT) {
        return err;
    }
    if (is_global) {
        if (err) {
            verbose(env, "Caller passes invalid args into func#%d\n", subprog);
            return err;
        } else {
            if (env->log.level & BPF_LOG_LEVEL) {
                verbose(env, "Func#%d is global and valid. Skipping.\n", subprog);
            }
            clear_caller_saved_regs(env, caller->regs);

            /* All global functions return a 64-bit SCALAR_VALUE */
            mark_reg_unknown(env, caller->regs, BPF_REG_0);
            caller->regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG;

            /* continue with next insn after call */
            return 0;
        }
    }

    callee = kzalloc(sizeof(*callee), GFP_KERNEL);
    if (!callee) {
        return -ENOMEM;
    }
    state->frame[state->curframe + 1] = callee;

    /* callee cannot access r0, r6 - r9 for reading and has to write
     * into its own stack before reading from it.
     * callee can read/write into caller's stack
     */
    init_func_state(env, callee,
                    /* remember the callsite, it will be used by bpf_exit */
                    *insn_idx /* callsite */, state->curframe + 1 /* frameno within this callchain */,
                    subprog /* subprog number within this prog */);

    /* Transfer references to the callee */
    err = transfer_reference_state(callee, caller);
    if (err) {
        return err;
    }

    /* copy r1 - r5 args that callee can access.  The copy includes parent
     * pointers, which connects us up to the liveness chain
     */
    for (i = BPF_REG_1; i <= BPF_REG_5; i++) {
        callee->regs[i] = caller->regs[i];
    }

    clear_caller_saved_regs(env, caller->regs);

    /* only increment it after check_reg_arg() finished */
    state->curframe++;

    /* and go analyze first insn of the callee */
    *insn_idx = target_insn;

    if (env->log.level & BPF_LOG_LEVEL) {
        verbose(env, "caller:\n");
        print_verifier_state(env, caller);
        verbose(env, "callee:\n");
        print_verifier_state(env, callee);
    }
    return 0;
}

static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx)
{
    struct bpf_verifier_state *state = env->cur_state;
    struct bpf_func_state *caller, *callee;
    struct bpf_reg_state *r0;
    int err;

    callee = state->frame[state->curframe];
    r0 = &callee->regs[BPF_REG_0];
    if (r0->type == PTR_TO_STACK) {
        /* technically it's ok to return caller's stack pointer
         * (or caller's caller's pointer) back to the caller,
         * since these pointers are valid. Only current stack
         * pointer will be invalid as soon as function exits,
         * but let's be conservative
         */
        verbose(env, "cannot return stack pointer to the caller\n");
        return -EINVAL;
    }

    state->curframe--;
    caller = state->frame[state->curframe];
    /* return to the caller whatever r0 had in the callee */
    caller->regs[BPF_REG_0] = *r0;

    /* Transfer references to the caller */
    err = transfer_reference_state(caller, callee);
    if (err) {
        return err;
    }

    *insn_idx = callee->callsite + 1;
    if (env->log.level & BPF_LOG_LEVEL) {
        verbose(env, "returning from callee:\n");
        print_verifier_state(env, callee);
        verbose(env, "to caller at %d:\n", *insn_idx);
        print_verifier_state(env, caller);
    }
    /* clear everything in the callee */
    free_func_state(callee);
    state->frame[state->curframe + 1] = NULL;
    return 0;
}

static void do_refine_retval_range(struct bpf_reg_state *regs, int ret_type, int func_id,
                                   struct bpf_call_arg_meta *meta)
{
    struct bpf_reg_state *ret_reg = &regs[BPF_REG_0];

    if (ret_type != RET_INTEGER ||
        (func_id != BPF_FUNC_get_stack && func_id != BPF_FUNC_probe_read_str &&
         func_id != BPF_FUNC_probe_read_kernel_str && func_id != BPF_FUNC_probe_read_user_str)) {
        return;
    }

    ret_reg->smax_value = meta->msize_max_value;
    ret_reg->s32_max_value = meta->msize_max_value;
    ret_reg->smin_value = -MAX_ERRNO;
    ret_reg->s32_min_value = -MAX_ERRNO;
    reg_bounds_sync(ret_reg);
}

static int record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta, int func_id, int insn_idx)
{
    struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
    struct bpf_map *map = meta->map_ptr;

    if (func_id != BPF_FUNC_tail_call && func_id != BPF_FUNC_map_lookup_elem && func_id != BPF_FUNC_map_update_elem &&
        func_id != BPF_FUNC_map_delete_elem && func_id != BPF_FUNC_map_push_elem && func_id != BPF_FUNC_map_pop_elem &&
        func_id != BPF_FUNC_map_peek_elem) {
        return 0;
    }

    if (map == NULL) {
        verbose(env, "kernel subsystem misconfigured verifier\n");
        return -EINVAL;
    }

    /* In case of read-only, some additional restrictions
     * need to be applied in order to prevent altering the
     * state of the map from program side.
     */
    if ((map->map_flags & BPF_F_RDONLY_PROG) &&
        (func_id == BPF_FUNC_map_delete_elem || func_id == BPF_FUNC_map_update_elem ||
         func_id == BPF_FUNC_map_push_elem || func_id == BPF_FUNC_map_pop_elem)) {
        verbose(env, "write into map forbidden\n");
        return -EACCES;
    }

    if (!BPF_MAP_PTR(aux->map_ptr_state)) {
        bpf_map_ptr_store(aux, meta->map_ptr, !meta->map_ptr->bypass_spec_v1);
    } else if (BPF_MAP_PTR(aux->map_ptr_state) != meta->map_ptr) {
        bpf_map_ptr_store(aux, BPF_MAP_PTR_POISON, !meta->map_ptr->bypass_spec_v1);
    }
    return 0;
}

static int record_func_key(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta, int func_id, int insn_idx)
{
    struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
    struct bpf_reg_state *regs = cur_regs(env), *reg;
    struct bpf_map *map = meta->map_ptr;
    u64 val;
    int err;

    if (func_id != BPF_FUNC_tail_call) {
        return 0;
    }
    if (!map || map->map_type != BPF_MAP_TYPE_PROG_ARRAY) {
        verbose(env, "kernel subsystem misconfigured verifier\n");
        return -EINVAL;
    }

    reg = &regs[BPF_REG_3];
    val = reg->var_off.value;
    max = map->max_entries;

    if (!(register_is_const(reg) && val < max)) {
        bpf_map_key_store(aux, BPF_MAP_KEY_POISON);
        return 0;
    }

    err = mark_chain_precision(env, BPF_REG_3);
    if (err) {
        return err;
    }

    if (bpf_map_key_unseen(aux)) {
        bpf_map_key_store(aux, val);
    } else if (!bpf_map_key_poisoned(aux) && bpf_map_key_immediate(aux) != val) {
        bpf_map_key_store(aux, BPF_MAP_KEY_POISON);
    }
    return 0;
}

static int check_reference_leak(struct bpf_verifier_env *env)
{
    struct bpf_func_state *state = cur_func(env);
    int i;

    for (i = 0; i < state->acquired_refs; i++) {
        verbose(env, "Unreleased reference id=%d alloc_insn=%d\n", state->refs[i].id, state->refs[i].insn_idx);
    }
    return state->acquired_refs ? -EINVAL : 0;
}

static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn_idx)
{
    const struct bpf_func_proto *fn = NULL;
    enum bpf_return_type ret_type;
    enum bpf_type_flag ret_flag;
    struct bpf_reg_state *regs;
    struct bpf_call_arg_meta meta;
    bool changes_data;
    int i, err;

    /* find function prototype */
    if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) {
        verbose(env, "invalid func %s#%d\n", func_id_name(func_id), func_id);
        return -EINVAL;
    }

    if (env->ops->get_func_proto) {
        fn = env->ops->get_func_proto(func_id, env->prog);
    }
    if (!fn) {
        verbose(env, "unknown func %s#%d\n", func_id_name(func_id), func_id);
        return -EINVAL;
    }

    /* eBPF programs must be GPL compatible to use GPL-ed functions */
    if (!env->prog->gpl_compatible && fn->gpl_only) {
        verbose(env, "cannot call GPL-restricted function from non-GPL compatible program\n");
        return -EINVAL;
    }

    if (fn->allowed && !fn->allowed(env->prog)) {
        verbose(env, "helper call is not allowed in probe\n");
        return -EINVAL;
    }

    /* With LD_ABS/IND some JITs save/restore skb from r1. */
    changes_data = bpf_helper_changes_pkt_data(fn->func);
    if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) {
        verbose(env, "kernel subsystem misconfigured func %s#%d: r1 != ctx\n", func_id_name(func_id), func_id);
        return -EINVAL;
    }

    memset(&meta, 0, sizeof(meta));
    meta.pkt_access = fn->pkt_access;

    err = check_func_proto(fn, func_id);
    if (err) {
        verbose(env, "kernel subsystem misconfigured func %s#%d\n", func_id_name(func_id), func_id);
        return err;
    }

    meta.func_id = func_id;
    /* check args */
    for (i = 0; i < 5; i++) {
        err = check_func_arg(env, i, &meta, fn);
        if (err) {
            return err;
        }
    }

    err = record_func_map(env, &meta, func_id, insn_idx);
    if (err) {
        return err;
    }

    err = record_func_key(env, &meta, func_id, insn_idx);
    if (err) {
        return err;
    }

    /* Mark slots with STACK_MISC in case of raw mode, stack offset
     * is inferred from register state.
     */
    for (i = 0; i < meta.access_size; i++) {
        err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B, BPF_WRITE, -1, false);
        if (err) {
            return err;
        }
    }

    if (func_id == BPF_FUNC_tail_call) {
        err = check_reference_leak(env);
        if (err) {
            verbose(env, "tail_call would lead to reference leak\n");
            return err;
        }
    } else if (is_release_function(func_id)) {
        err = release_reference(env, meta.ref_obj_id);
        if (err) {
            verbose(env, "func %s#%d reference has not been acquired before\n", func_id_name(func_id), func_id);
            return err;
        }
    }

    regs = cur_regs(env);
    /* check that flags argument in get_local_storage(map, flags) is 0,
     * this is required because get_local_storage() can't return an error.
     */
    if (func_id == BPF_FUNC_get_local_storage && !register_is_null(&regs[BPF_REG_2])) {
        verbose(env, "get_local_storage() doesn't support non-zero flags\n");
        return -EINVAL;
    }

    /* reset caller saved regs */
    for (i = 0; i < CALLER_SAVED_REGS; i++) {
        mark_reg_not_init(env, regs, caller_saved[i]);
        check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
    }

    /* helper call returns 64-bit value. */
    regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG;

    /* update return register (already marked as written above) */
    ret_type = fn->ret_type;
    ret_flag = type_flag(fn->ret_type);
    if (ret_type == RET_INTEGER) {
        /* sets type to SCALAR_VALUE */
        mark_reg_unknown(env, regs, BPF_REG_0);
    } else if (ret_type == RET_VOID) {
        regs[BPF_REG_0].type = NOT_INIT;
    } else if (base_type(ret_type) == RET_PTR_TO_MAP_VALUE) {
        /* There is no offset yet applied, variable or fixed */
        mark_reg_known_zero(env, regs, BPF_REG_0);
        /* remember map_ptr, so that check_map_access()
         * can check 'value_size' boundary of memory access
         * to map element returned from bpf_map_lookup_elem()
         */
        if (meta.map_ptr == NULL) {
            verbose(env, "kernel subsystem misconfigured verifier\n");
            return -EINVAL;
        }
        regs[BPF_REG_0].map_ptr = meta.map_ptr;
        regs[BPF_REG_0].type = PTR_TO_MAP_VALUE | ret_flag;
        if (!type_may_be_null(ret_type) && map_value_has_spin_lock(meta.map_ptr)) {
            regs[BPF_REG_0].id = ++env->id_gen;
        }
    } else if (base_type(ret_type) == RET_PTR_TO_SOCKET) {
        mark_reg_known_zero(env, regs, BPF_REG_0);
        regs[BPF_REG_0].type = PTR_TO_SOCKET | ret_flag;
    } else if (base_type(ret_type) == RET_PTR_TO_SOCK_COMMON) {
        mark_reg_known_zero(env, regs, BPF_REG_0);
        regs[BPF_REG_0].type = PTR_TO_SOCK_COMMON | ret_flag;
    } else if (base_type(ret_type) == RET_PTR_TO_TCP_SOCK) {
        mark_reg_known_zero(env, regs, BPF_REG_0);
        regs[BPF_REG_0].type = PTR_TO_TCP_SOCK | ret_flag;
    } else if (base_type(ret_type) == RET_PTR_TO_ALLOC_MEM) {
        mark_reg_known_zero(env, regs, BPF_REG_0);
        regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag;
        regs[BPF_REG_0].mem_size = meta.mem_size;
    } else if (base_type(ret_type) == RET_PTR_TO_MEM_OR_BTF_ID) {
        const struct btf_type *t;

        mark_reg_known_zero(env, regs, BPF_REG_0);
        t = btf_type_skip_modifiers(btf_vmlinux, meta.ret_btf_id, NULL);
        if (!btf_type_is_struct(t)) {
            u32 tsize;
            const struct btf_type *ret;
            const char *tname;

            /* resolve the type size of ksym. */
            ret = btf_resolve_size(btf_vmlinux, t, &tsize);
            if (IS_ERR(ret)) {
                tname = btf_name_by_offset(btf_vmlinux, t->name_off);
                verbose(env, "unable to resolve the size of type '%s': %ld\n", tname, PTR_ERR(ret));
                return -EINVAL;
            }
            regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag;
            regs[BPF_REG_0].mem_size = tsize;
        } else {
            /* MEM_RDONLY may be carried from ret_flag, but it
             * doesn't apply on PTR_TO_BTF_ID. Fold it, otherwise
             * it will confuse the check of PTR_TO_BTF_ID in
             * check_mem_access().
             */
            ret_flag &= ~MEM_RDONLY;

            regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag;
            regs[BPF_REG_0].btf_id = meta.ret_btf_id;
        }
    } else if (base_type(ret_type) == RET_PTR_TO_BTF_ID) {
        int ret_btf_id;

        mark_reg_known_zero(env, regs, BPF_REG_0);
        regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag;
        ret_btf_id = *fn->ret_btf_id;
        if (ret_btf_id == 0) {
            verbose(env, "invalid return type %u of func %s#%d\n", base_type(ret_type), func_id_name(func_id), func_id);
            return -EINVAL;
        }
        regs[BPF_REG_0].btf_id = ret_btf_id;
    } else {
        verbose(env, "unknown return type %u of func %s#%d\n", base_type(ret_type), func_id_name(func_id), func_id);
        return -EINVAL;
    }

    if (type_may_be_null(regs[BPF_REG_0].type)) {
        regs[BPF_REG_0].id = ++env->id_gen;
    }

    if (is_ptr_cast_function(func_id)) {
        /* For release_reference() */
        regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id;
    } else if (is_acquire_function(func_id, meta.map_ptr)) {
        int id = acquire_reference_state(env, insn_idx);
        if (id < 0) {
            return id;
        }
        /* For mark_ptr_or_null_reg() */
        regs[BPF_REG_0].id = id;
        /* For release_reference() */
        regs[BPF_REG_0].ref_obj_id = id;
    }

    do_refine_retval_range(regs, fn->ret_type, func_id, &meta);

    err = check_map_func_compatibility(env, meta.map_ptr, func_id);
    if (err) {
        return err;
    }

    if ((func_id == BPF_FUNC_get_stack || func_id == BPF_FUNC_get_task_stack) && !env->prog->has_callchain_buf) {
        const char *err_str;

#ifdef CONFIG_PERF_EVENTS
        err = get_callchain_buffers(sysctl_perf_event_max_stack);
        err_str = "cannot get callchain buffer for func %s#%d\n";
#else
        err = -ENOTSUPP;
        err_str = "func %s#%d not supported without CONFIG_PERF_EVENTS\n";
#endif
        if (err) {
            verbose(env, err_str, func_id_name(func_id), func_id);
            return err;
        }

        env->prog->has_callchain_buf = true;
    }

    if (func_id == BPF_FUNC_get_stackid || func_id == BPF_FUNC_get_stack) {
        env->prog->call_get_stack = true;
    }

    if (changes_data) {
        clear_all_pkt_pointers(env);
    }
    return 0;
}

static bool signed_add_overflows(s64 a, s64 b)
{
    /* Do the add in u64, where overflow is well-defined */
    s64 res = (s64)((u64)a + (u64)b);

    if (b < 0) {
        return res > a;
    }
    return res < a;
}

static bool signed_add32_overflows(s32 a, s32 b)
{
    /* Do the add in u32, where overflow is well-defined */
    s32 res = (s32)((u32)a + (u32)b);

    if (b < 0) {
        return res > a;
    }
    return res < a;
}

static bool signed_sub_overflows(s64 a, s64 b)
{
    /* Do the sub in u64, where overflow is well-defined */
    s64 res = (s64)((u64)a - (u64)b);

    if (b < 0) {
        return res < a;
    }
    return res > a;
}

static bool signed_sub32_overflows(s32 a, s32 b)
{
    /* Do the sub in u32, where overflow is well-defined */
    s32 res = (s32)((u32)a - (u32)b);

    if (b < 0) {
        return res < a;
    }
    return res > a;
}

static bool check_reg_sane_offset(struct bpf_verifier_env *env, const struct bpf_reg_state *reg, enum bpf_reg_type type)
{
    bool known = tnum_is_const(reg->var_off);
    s64 val = reg->var_off.value;
    s64 smin = reg->smin_value;

    if (known && (val >= BPF_MAX_VAR_OFF || val <= -BPF_MAX_VAR_OFF)) {
        verbose(env, "math between %s pointer and %lld is not allowed\n", reg_type_str(env, type), val);
        return false;
    }

    if (reg->off >= BPF_MAX_VAR_OFF || reg->off <= -BPF_MAX_VAR_OFF) {
        verbose(env, "%s pointer offset %d is not allowed\n", reg_type_str(env, type), reg->off);
        return false;
    }

    if (smin == S64_MIN) {
        verbose(env, "math between %s pointer and register with unbounded min value is not allowed\n",
                reg_type_str(env, type));
        return false;
    }

    if (smin >= BPF_MAX_VAR_OFF || smin <= -BPF_MAX_VAR_OFF) {
        verbose(env, "value %lld makes %s pointer be out of bounds\n", smin, reg_type_str(env, type));
        return false;
    }

    return true;
}

static struct bpf_insn_aux_data *cur_aux(struct bpf_verifier_env *env)
{
    return &env->insn_aux_data[env->insn_idx];
}

enum {
    REASON_BOUNDS = -1,
    REASON_TYPE = -2,
    REASON_PATHS = -3,
    REASON_LIMIT = -4,
    REASON_STACK = -5,
};

static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg, u32 *alu_limit, bool mask_to_left)
{
    u32 max = 0, ptr_limit = 0;

    switch (ptr_reg->type) {
        case PTR_TO_STACK:
            /* Offset 0 is out-of-bounds, but acceptable start for the
             * left direction, see BPF_REG_FP. Also, unknown scalar
             * offset where we would need to deal with min/max bounds is
             * currently prohibited for unprivileged.
             */
            max = MAX_BPF_STACK + mask_to_left;
            ptr_limit = -(ptr_reg->var_off.value + ptr_reg->off);
            break;
        case PTR_TO_MAP_VALUE:
            max = ptr_reg->map_ptr->value_size;
            ptr_limit = (mask_to_left ? ptr_reg->smin_value : ptr_reg->umax_value) + ptr_reg->off;
            break;
        default:
            return REASON_TYPE;
    }

    if (ptr_limit >= max) {
        return REASON_LIMIT;
    }
    *alu_limit = ptr_limit;
    return 0;
}

static bool can_skip_alu_sanitation(const struct bpf_verifier_env *env, const struct bpf_insn *insn)
{
    return env->bypass_spec_v1 || BPF_SRC(insn->code) == BPF_K;
}

static int update_alu_sanitation_state(struct bpf_insn_aux_data *aux, u32 alu_state, u32 alu_limit)
{
    /* If we arrived here from different branches with different
     * state or limits to sanitize, then this won't work.
     */
    if (aux->alu_state && (aux->alu_state != alu_state || aux->alu_limit != alu_limit)) {
        return REASON_PATHS;
    }

    /* Corresponding fixup done in fixup_bpf_calls(). */
    aux->alu_state = alu_state;
    aux->alu_limit = alu_limit;
    return 0;
}

static int sanitize_val_alu(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
    struct bpf_insn_aux_data *aux = cur_aux(env);

    if (can_skip_alu_sanitation(env, insn)) {
        return 0;
    }

    return update_alu_sanitation_state(aux, BPF_ALU_NON_POINTER, 0);
}

static bool sanitize_needed(u8 opcode)
{
    return opcode == BPF_ADD || opcode == BPF_SUB;
}

struct bpf_sanitize_info {
    struct bpf_insn_aux_data aux;
    bool mask_to_left;
};

static struct bpf_verifier_state *sanitize_speculative_path(struct bpf_verifier_env *env, const struct bpf_insn *insn,
                                                            u32 next_idx, u32 curr_idx)
{
    struct bpf_verifier_state *branch;
    struct bpf_reg_state *regs;

    branch = push_stack(env, next_idx, curr_idx, true);
    if (branch && insn) {
        regs = branch->frame[branch->curframe]->regs;
        if (BPF_SRC(insn->code) == BPF_K) {
            mark_reg_unknown(env, regs, insn->dst_reg);
        } else if (BPF_SRC(insn->code) == BPF_X) {
            mark_reg_unknown(env, regs, insn->dst_reg);
            mark_reg_unknown(env, regs, insn->src_reg);
        }
    }
    return branch;
}

static int sanitize_ptr_alu(struct bpf_verifier_env *env, struct bpf_insn *insn, const struct bpf_reg_state *ptr_reg,
                            const struct bpf_reg_state *off_reg, struct bpf_reg_state *dst_reg,
                            struct bpf_sanitize_info *info, const bool commit_window)
{
    struct bpf_insn_aux_data *aux = commit_window ? cur_aux(env) : &info->aux;
    struct bpf_verifier_state *vstate = env->cur_state;
    bool off_is_imm = tnum_is_const(off_reg->var_off);
    bool off_is_neg = off_reg->smin_value < 0;
    bool ptr_is_dst_reg = ptr_reg == dst_reg;
    u8 opcode = BPF_OP(insn->code);
    u32 alu_state, alu_limit;
    struct bpf_reg_state tmp;
    bool ret;
    int err;

    if (can_skip_alu_sanitation(env, insn)) {
        return 0;
    }

    /* We already marked aux for masking from non-speculative
     * paths, thus we got here in the first place. We only care
     * to explore bad access from here.
     */
    if (vstate->speculative) {
        goto do_sim;
    }

    if (!commit_window) {
        if (!tnum_is_const(off_reg->var_off) && (off_reg->smin_value < 0) != (off_reg->smax_value < 0)) {
            return REASON_BOUNDS;
        }

        info->mask_to_left = (opcode == BPF_ADD && off_is_neg) || (opcode == BPF_SUB && !off_is_neg);
    }

    err = retrieve_ptr_limit(ptr_reg, &alu_limit, info->mask_to_left);
    if (err < 0) {
        return err;
    }

    if (commit_window) {
        /* In commit phase we narrow the masking window based on
         * the observed pointer move after the simulated operation.
         */
        alu_state = info->aux.alu_state;
        alu_limit = abs(info->aux.alu_limit - alu_limit);
    } else {
        alu_state = off_is_neg ? BPF_ALU_NEG_VALUE : 0;
        alu_state |= off_is_imm ? BPF_ALU_IMMEDIATE : 0;
        alu_state |= ptr_is_dst_reg ? BPF_ALU_SANITIZE_SRC : BPF_ALU_SANITIZE_DST;

        /* Limit pruning on unknown scalars to enable deep search for
         * potential masking differences from other program paths.
         */
        if (!off_is_imm) {
            env->explore_alu_limits = true;
        }
    }

    err = update_alu_sanitation_state(aux, alu_state, alu_limit);
    if (err < 0) {
        return err;
    }
do_sim:
    /* If we're in commit phase, we're done here given we already
     * pushed the truncated dst_reg into the speculative verification
     * stack.
     *
     * Also, when register is a known constant, we rewrite register-based
     * operation to immediate-based, and thus do not need masking (and as
     * a consequence, do not need to simulate the zero-truncation either).
     */
    if (commit_window || off_is_imm) {
        return 0;
    }

    /* Simulate and find potential out-of-bounds access under
     * speculative execution from truncation as a result of
     * masking when off was not within expected range. If off
     * sits in dst, then we temporarily need to move ptr there
     * to simulate dst (== 0) +/-= ptr. Needed, for example,
     * for cases where we use K-based arithmetic in one direction
     * and truncated reg-based in the other in order to explore
     * bad access.
     */
    if (!ptr_is_dst_reg) {
        tmp = *dst_reg;
        *dst_reg = *ptr_reg;
    }
    ret = sanitize_speculative_path(env, NULL, env->insn_idx + 1, env->insn_idx);
    if (!ptr_is_dst_reg && ret) {
        *dst_reg = tmp;
    }
    return !ret ? REASON_STACK : 0;
}

static void sanitize_mark_insn_seen(struct bpf_verifier_env *env)
{
    struct bpf_verifier_state *vstate = env->cur_state;

    /* If we simulate paths under speculation, we don't update the
     * insn as 'seen' such that when we verify unreachable paths in
     * the non-speculative domain, sanitize_dead_code() can still
     * rewrite/sanitize them.
     */
    if (!vstate->speculative) {
        env->insn_aux_data[env->insn_idx].seen = env->pass_cnt;
    }
}

static int sanitize_err(struct bpf_verifier_env *env, const struct bpf_insn *insn, int reason,
                        const struct bpf_reg_state *off_reg, const struct bpf_reg_state *dst_reg)
{
    static const char *err = "pointer arithmetic with it prohibited for !root";
    const char *op = BPF_OP(insn->code) == BPF_ADD ? "add" : "sub";
    u32 dst = insn->dst_reg, src = insn->src_reg;

    switch (reason) {
        case REASON_BOUNDS:
            verbose(env, "R%d has unknown scalar with mixed signed bounds, %s\n", off_reg == dst_reg ? dst : src, err);
            break;
        case REASON_TYPE:
            verbose(env, "R%d has pointer with unsupported alu operation, %s\n", off_reg == dst_reg ? src : dst, err);
            break;
        case REASON_PATHS:
            verbose(env, "R%d tried to %s from different maps, paths or scalars, %s\n", dst, op, err);
            break;
        case REASON_LIMIT:
            verbose(env, "R%d tried to %s beyond pointer bounds, %s\n", dst, op, err);
            break;
        case REASON_STACK:
            verbose(env, "R%d could not be pushed for speculative verification, %s\n", dst, err);
            break;
        default:
            verbose(env, "verifier internal error: unknown reason (%d)\n", reason);
            break;
    }

    return -EACCES;
}

/* check that stack access falls within stack limits and that 'reg' doesn't
 * have a variable offset.
 *
 * Variable offset is prohibited for unprivileged mode for simplicity since it
 * requires corresponding support in Spectre masking for stack ALU.  See also
 * retrieve_ptr_limit().
 *
 *
 * 'off' includes 'reg->off'.
 */
static int check_stack_access_for_ptr_arithmetic(struct bpf_verifier_env *env, int regno,
                                                 const struct bpf_reg_state *reg, int off)
{
    if (!tnum_is_const(reg->var_off)) {
        char tn_buf[48];

        tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
        verbose(env, "R%d variable stack access prohibited for !root, var_off=%s off=%d\n", regno, tn_buf, off);
        return -EACCES;
    }

    if (off >= 0 || off < -MAX_BPF_STACK) {
        verbose(env,
                "R%d stack pointer arithmetic goes out of range, "
                "prohibited for !root; off=%d\n",
                regno, off);
        return -EACCES;
    }

    return 0;
}

static int sanitize_check_bounds(struct bpf_verifier_env *env, const struct bpf_insn *insn,
                                 const struct bpf_reg_state *dst_reg)
{
    u32 dst = insn->dst_reg;

    /* For unprivileged we require that resulting offset must be in bounds
     * in order to be able to sanitize access later on.
     */
    if (env->bypass_spec_v1) {
        return 0;
    }

    switch (dst_reg->type) {
        case PTR_TO_STACK:
            if (check_stack_access_for_ptr_arithmetic(env, dst, dst_reg, dst_reg->off + dst_reg->var_off.value)) {
                return -EACCES;
            }
            break;
        case PTR_TO_MAP_VALUE:
            if (check_map_access(env, dst, dst_reg->off, 1, false)) {
                verbose(env,
                        "R%d pointer arithmetic of map value goes out of range, "
                        "prohibited for !root\n",
                        dst);
                return -EACCES;
            }
            break;
        default:
            break;
    }

    return 0;
}

/* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off.
 * Caller should also handle BPF_MOV case separately.
 * If we return -EACCES, caller may want to try again treating pointer as a
 * scalar.  So we only emit a diagnostic if !env->allow_ptr_leaks.
 */
static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, struct bpf_insn *insn,
                                   const struct bpf_reg_state *ptr_reg, const struct bpf_reg_state *off_reg)
{
    struct bpf_verifier_state *vstate = env->cur_state;
    struct bpf_func_state *state = vstate->frame[vstate->curframe];
    struct bpf_reg_state *regs = state->regs, *dst_reg;
    bool known = tnum_is_const(off_reg->var_off);
    s64 smin_val = off_reg->smin_value, smax_val = off_reg->smax_value, smin_ptr = ptr_reg->smin_value,
        smax_ptr = ptr_reg->smax_value;
    u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value, umin_ptr = ptr_reg->umin_value,
        umax_ptr = ptr_reg->umax_value;
    struct bpf_sanitize_info info = {};
    u8 opcode = BPF_OP(insn->code);
    u32 dst = insn->dst_reg;
    int ret;

    dst_reg = &regs[dst];

    if ((known && (smin_val != smax_val || umin_val != umax_val)) || smin_val > smax_val || umin_val > umax_val) {
        /* Taint dst register if offset had invalid bounds derived from
         * e.g. dead branches.
         */
        __mark_reg_unknown(env, dst_reg);
        return 0;
    }

    if (BPF_CLASS(insn->code) != BPF_ALU64) {
        /* 32-bit ALU ops on pointers produce (meaningless) scalars */
        if (opcode == BPF_SUB && env->allow_ptr_leaks) {
            __mark_reg_unknown(env, dst_reg);
            return 0;
        }

        verbose(env, "R%d 32-bit pointer arithmetic prohibited\n", dst);
        return -EACCES;
    }

    if (ptr_reg->type & PTR_MAYBE_NULL) {
        verbose(env, "R%d pointer arithmetic on %s prohibited, null-check it first\n", dst,
                reg_type_str(env, ptr_reg->type));
        return -EACCES;
    }

    switch (base_type(ptr_reg->type)) {
        case CONST_PTR_TO_MAP:
            /* smin_val represents the known value */
            if (known && smin_val == 0 && opcode == BPF_ADD) {
                break;
            }
            fallthrough;
        case PTR_TO_PACKET_END:
        case PTR_TO_SOCKET:
        case PTR_TO_SOCK_COMMON:
        case PTR_TO_TCP_SOCK:
        case PTR_TO_XDP_SOCK:
            reject:
            verbose(env, "R%d pointer arithmetic on %s prohibited\n", dst, reg_type_str(env, ptr_reg->type));
            return -EACCES;
        default:
            if (type_may_be_null(ptr_reg->type)) {
                goto reject;
            }
            break;
    }

    /* In case of 'scalar += pointer', dst_reg inherits pointer type and id.
     * The id may be overwritten later if we create a new variable offset.
     */
    dst_reg->type = ptr_reg->type;
    dst_reg->id = ptr_reg->id;

    if (!check_reg_sane_offset(env, off_reg, ptr_reg->type) || !check_reg_sane_offset(env, ptr_reg, ptr_reg->type)) {
        return -EINVAL;
    }

    /* pointer types do not carry 32-bit bounds at the moment. */
    verifier_mark_reg32_unbounded(dst_reg);

    if (sanitize_needed(opcode)) {
        ret = sanitize_ptr_alu(env, insn, ptr_reg, off_reg, dst_reg, &info, false);
        if (ret < 0) {
            return sanitize_err(env, insn, ret, off_reg, dst_reg);
        }
    }

    switch (opcode) {
        case BPF_ADD:
            /* We can take a fixed offset as long as it doesn't overflow
             * the s32 'off' field
             */
            if (known && (ptr_reg->off + smin_val == (s64)(s32)(ptr_reg->off + smin_val))) {
                /* pointer += K.  Accumulate it into fixed offset */
                dst_reg->smin_value = smin_ptr;
                dst_reg->smax_value = smax_ptr;
                dst_reg->umin_value = umin_ptr;
                dst_reg->umax_value = umax_ptr;
                dst_reg->var_off = ptr_reg->var_off;
                dst_reg->off = ptr_reg->off + smin_val;
                dst_reg->raw = ptr_reg->raw;
                break;
            }
            /* A new variable offset is created.  Note that off_reg->off
             * == 0, since it's a scalar.
             * dst_reg gets the pointer type and since some positive
             * integer value was added to the pointer, give it a new 'id'
             * if it's a PTR_TO_PACKET.
             * this creates a new 'base' pointer, off_reg (variable) gets
             * added into the variable offset, and we copy the fixed offset
             * from ptr_reg.
             */
            if (signed_add_overflows(smin_ptr, smin_val) || signed_add_overflows(smax_ptr, smax_val)) {
                dst_reg->smin_value = S64_MIN;
                dst_reg->smax_value = S64_MAX;
            } else {
                dst_reg->smin_value = smin_ptr + smin_val;
                dst_reg->smax_value = smax_ptr + smax_val;
            }
            if (umin_ptr + umin_val < umin_ptr || umax_ptr + umax_val < umax_ptr) {
                dst_reg->umin_value = 0;
                dst_reg->umax_value = U64_MAX;
            } else {
                dst_reg->umin_value = umin_ptr + umin_val;
                dst_reg->umax_value = umax_ptr + umax_val;
            }
            dst_reg->var_off = tnum_add(ptr_reg->var_off, off_reg->var_off);
            dst_reg->off = ptr_reg->off;
            dst_reg->raw = ptr_reg->raw;
            if (reg_is_pkt_pointer(ptr_reg)) {
                dst_reg->id = ++env->id_gen;
                /* something was added to pkt_ptr, set range to zero */
                dst_reg->raw = 0;
            }
            break;
        case BPF_SUB:
            if (dst_reg == off_reg) {
                /* scalar -= pointer.  Creates an unknown scalar */
                verbose(env, "R%d tried to subtract pointer from scalar\n", dst);
                return -EACCES;
            }
            /* We don't allow subtraction from FP, because (according to
             * test_verifier.c test "invalid fp arithmetic", JITs might not
             * be able to deal with it.
             */
            if (ptr_reg->type == PTR_TO_STACK) {
                verbose(env, "R%d subtraction from stack pointer prohibited\n", dst);
                return -EACCES;
            }
            if (known && (ptr_reg->off - smin_val == (s64)(s32)(ptr_reg->off - smin_val))) {
                /* pointer -= K.  Subtract it from fixed offset */
                dst_reg->smin_value = smin_ptr;
                dst_reg->smax_value = smax_ptr;
                dst_reg->umin_value = umin_ptr;
                dst_reg->umax_value = umax_ptr;
                dst_reg->var_off = ptr_reg->var_off;
                dst_reg->id = ptr_reg->id;
                dst_reg->off = ptr_reg->off - smin_val;
                dst_reg->raw = ptr_reg->raw;
                break;
            }
            /* A new variable offset is created.  If the subtrahend is known
             * nonnegative, then any reg->range we had before is still good.
             */
            if (signed_sub_overflows(smin_ptr, smax_val) || signed_sub_overflows(smax_ptr, smin_val)) {
                /* Overflow possible, we know nothing */
                dst_reg->smin_value = S64_MIN;
                dst_reg->smax_value = S64_MAX;
            } else {
                dst_reg->smin_value = smin_ptr - smax_val;
                dst_reg->smax_value = smax_ptr - smin_val;
            }
            if (umin_ptr < umax_val) {
                /* Overflow possible, we know nothing */
                dst_reg->umin_value = 0;
                dst_reg->umax_value = U64_MAX;
            } else {
                /* Cannot overflow (as long as bounds are consistent) */
                dst_reg->umin_value = umin_ptr - umax_val;
                dst_reg->umax_value = umax_ptr - umin_val;
            }
            dst_reg->var_off = tnum_sub(ptr_reg->var_off, off_reg->var_off);
            dst_reg->off = ptr_reg->off;
            dst_reg->raw = ptr_reg->raw;
            if (reg_is_pkt_pointer(ptr_reg)) {
                dst_reg->id = ++env->id_gen;
                /* something was added to pkt_ptr, set range to zero */
                if (smin_val < 0) {
                    dst_reg->raw = 0;
                }
            }
            break;
        case BPF_AND:
        case BPF_OR:
        case BPF_XOR:
            /* bitwise ops on pointers are troublesome, prohibit. */
            verbose(env, "R%d bitwise operator %s on pointer prohibited\n", dst, bpf_alu_string[opcode >> 0x4]);
            return -EACCES;
        default:
            /* other operators (e.g. MUL,LSH) produce non-pointer results */
            verbose(env, "R%d pointer arithmetic with %s operator prohibited\n", dst, bpf_alu_string[opcode >> 0x4]);
            return -EACCES;
    }

    if (!check_reg_sane_offset(env, dst_reg, ptr_reg->type)) {
        return -EINVAL;
    }

    reg_bounds_sync(dst_reg);

    if (sanitize_check_bounds(env, insn, dst_reg) < 0) {
        return -EACCES;
    }
    if (sanitize_needed(opcode)) {
        ret = sanitize_ptr_alu(env, insn, dst_reg, off_reg, dst_reg, &info, true);
        if (ret < 0) {
            return sanitize_err(env, insn, ret, off_reg, dst_reg);
        }
    }

    return 0;
}

static void scalar32_min_max_add(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    s32 smin_val = src_reg->s32_min_value;
    s32 smax_val = src_reg->s32_max_value;
    u32 umin_val = src_reg->u32_min_value;
    u32 umax_val = src_reg->u32_max_value;

    if (signed_add32_overflows(dst_reg->s32_min_value, smin_val) ||
        signed_add32_overflows(dst_reg->s32_max_value, smax_val)) {
        dst_reg->s32_min_value = S32_MIN;
        dst_reg->s32_max_value = S32_MAX;
    } else {
        dst_reg->s32_min_value += smin_val;
        dst_reg->s32_max_value += smax_val;
    }
    if (dst_reg->u32_min_value + umin_val < umin_val || dst_reg->u32_max_value + umax_val < umax_val) {
        dst_reg->u32_min_value = 0;
        dst_reg->u32_max_value = U32_MAX;
    } else {
        dst_reg->u32_min_value += umin_val;
        dst_reg->u32_max_value += umax_val;
    }
}

static void scalar_min_max_add(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    s64 smin_val = src_reg->smin_value;
    s64 smax_val = src_reg->smax_value;
    u64 umin_val = src_reg->umin_value;
    u64 umax_val = src_reg->umax_value;

    if (signed_add_overflows(dst_reg->smin_value, smin_val) || signed_add_overflows(dst_reg->smax_value, smax_val)) {
        dst_reg->smin_value = S64_MIN;
        dst_reg->smax_value = S64_MAX;
    } else {
        dst_reg->smin_value += smin_val;
        dst_reg->smax_value += smax_val;
    }
    if (dst_reg->umin_value + umin_val < umin_val || dst_reg->umax_value + umax_val < umax_val) {
        dst_reg->umin_value = 0;
        dst_reg->umax_value = U64_MAX;
    } else {
        dst_reg->umin_value += umin_val;
        dst_reg->umax_value += umax_val;
    }
}

static void scalar32_min_max_sub(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    s32 smin_val = src_reg->s32_min_value;
    s32 smax_val = src_reg->s32_max_value;
    u32 umin_val = src_reg->u32_min_value;
    u32 umax_val = src_reg->u32_max_value;

    if (signed_sub32_overflows(dst_reg->s32_min_value, smax_val) ||
        signed_sub32_overflows(dst_reg->s32_max_value, smin_val)) {
        /* Overflow possible, we know nothing */
        dst_reg->s32_min_value = S32_MIN;
        dst_reg->s32_max_value = S32_MAX;
    } else {
        dst_reg->s32_min_value -= smax_val;
        dst_reg->s32_max_value -= smin_val;
    }
    if (dst_reg->u32_min_value < umax_val) {
        /* Overflow possible, we know nothing */
        dst_reg->u32_min_value = 0;
        dst_reg->u32_max_value = U32_MAX;
    } else {
        /* Cannot overflow (as long as bounds are consistent) */
        dst_reg->u32_min_value -= umax_val;
        dst_reg->u32_max_value -= umin_val;
    }
}

static void scalar_min_max_sub(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    s64 smin_val = src_reg->smin_value;
    s64 smax_val = src_reg->smax_value;
    u64 umin_val = src_reg->umin_value;
    u64 umax_val = src_reg->umax_value;

    if (signed_sub_overflows(dst_reg->smin_value, smax_val) || signed_sub_overflows(dst_reg->smax_value, smin_val)) {
        /* Overflow possible, we know nothing */
        dst_reg->smin_value = S64_MIN;
        dst_reg->smax_value = S64_MAX;
    } else {
        dst_reg->smin_value -= smax_val;
        dst_reg->smax_value -= smin_val;
    }
    if (dst_reg->umin_value < umax_val) {
        /* Overflow possible, we know nothing */
        dst_reg->umin_value = 0;
        dst_reg->umax_value = U64_MAX;
    } else {
        /* Cannot overflow (as long as bounds are consistent) */
        dst_reg->umin_value -= umax_val;
        dst_reg->umax_value -= umin_val;
    }
}

static void scalar32_min_max_mul(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    s32 smin_val = src_reg->s32_min_value;
    u32 umin_val = src_reg->u32_min_value;
    u32 umax_val = src_reg->u32_max_value;

    if (smin_val < 0 || dst_reg->s32_min_value < 0) {
        /* Ain't nobody got time to multiply that sign */
        verifier_mark_reg32_unbounded(dst_reg);
        return;
    }
    /* Both values are positive, so we can work with unsigned and
     * copy the result to signed (unless it exceeds S32_MAX).
     */
    if (umax_val > U16_MAX || dst_reg->u32_max_value > U16_MAX) {
        /* Potential overflow, we know nothing */
        verifier_mark_reg32_unbounded(dst_reg);
        return;
    }
    dst_reg->u32_min_value *= umin_val;
    dst_reg->u32_max_value *= umax_val;
    if (dst_reg->u32_max_value > S32_MAX) {
        /* Overflow possible, we know nothing */
        dst_reg->s32_min_value = S32_MIN;
        dst_reg->s32_max_value = S32_MAX;
    } else {
        dst_reg->s32_min_value = dst_reg->u32_min_value;
        dst_reg->s32_max_value = dst_reg->u32_max_value;
    }
}

static void scalar_min_max_mul(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    s64 smin_val = src_reg->smin_value;
    u64 umin_val = src_reg->umin_value;
    u64 umax_val = src_reg->umax_value;

    if (smin_val < 0 || dst_reg->smin_value < 0) {
        /* Ain't nobody got time to multiply that sign */
        verifier_mark_reg64_unbounded(dst_reg);
        return;
    }
    /* Both values are positive, so we can work with unsigned and
     * copy the result to signed (unless it exceeds S64_MAX).
     */
    if (umax_val > U32_MAX || dst_reg->umax_value > U32_MAX) {
        /* Potential overflow, we know nothing */
        verifier_mark_reg64_unbounded(dst_reg);
        return;
    }
    dst_reg->umin_value *= umin_val;
    dst_reg->umax_value *= umax_val;
    if (dst_reg->umax_value > S64_MAX) {
        /* Overflow possible, we know nothing */
        dst_reg->smin_value = S64_MIN;
        dst_reg->smax_value = S64_MAX;
    } else {
        dst_reg->smin_value = dst_reg->umin_value;
        dst_reg->smax_value = dst_reg->umax_value;
    }
}

static void scalar32_min_max_and(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    bool src_known = tnum_subreg_is_const(src_reg->var_off);
    bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
    struct tnum var32_off = tnum_subreg(dst_reg->var_off);
    s32 smin_val = src_reg->s32_min_value;
    u32 umax_val = src_reg->u32_max_value;

    if (src_known && dst_known) {
        verifier_mark_reg32_known(dst_reg, var32_off.value);
        return;
    }

    /* We get our minimum from the var_off, since that's inherently
     * bitwise.  Our maximum is the minimum of the operands' maxima.
     */
    dst_reg->u32_min_value = var32_off.value;
    dst_reg->u32_max_value = min(dst_reg->u32_max_value, umax_val);
    if (dst_reg->s32_min_value < 0 || smin_val < 0) {
        /* Lose signed bounds when ANDing negative numbers,
         * ain't nobody got time for that.
         */
        dst_reg->s32_min_value = S32_MIN;
        dst_reg->s32_max_value = S32_MAX;
    } else {
        /* ANDing two positives gives a positive, so safe to
         * cast result into s64.
         */
        dst_reg->s32_min_value = dst_reg->u32_min_value;
        dst_reg->s32_max_value = dst_reg->u32_max_value;
    }
}

static void scalar_min_max_and(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    bool src_known = tnum_is_const(src_reg->var_off);
    bool dst_known = tnum_is_const(dst_reg->var_off);
    s64 smin_val = src_reg->smin_value;
    u64 umax_val = src_reg->umax_value;

    if (src_known && dst_known) {
        verifier_mark_reg_known(dst_reg, dst_reg->var_off.value);
        return;
    }

    /* We get our minimum from the var_off, since that's inherently
     * bitwise.  Our maximum is the minimum of the operands' maxima.
     */
    dst_reg->umin_value = dst_reg->var_off.value;
    dst_reg->umax_value = min(dst_reg->umax_value, umax_val);
    if (dst_reg->smin_value < 0 || smin_val < 0) {
        /* Lose signed bounds when ANDing negative numbers,
         * ain't nobody got time for that.
         */
        dst_reg->smin_value = S64_MIN;
        dst_reg->smax_value = S64_MAX;
    } else {
        /* ANDing two positives gives a positive, so safe to
         * cast result into s64.
         */
        dst_reg->smin_value = dst_reg->umin_value;
        dst_reg->smax_value = dst_reg->umax_value;
    }
    /* We may learn something more from the var_off */
    verifier_update_reg_bounds(dst_reg);
}

static void scalar32_min_max_or(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    bool src_known = tnum_subreg_is_const(src_reg->var_off);
    bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
    struct tnum var32_off = tnum_subreg(dst_reg->var_off);
    s32 smin_val = src_reg->s32_min_value;
    u32 umin_val = src_reg->u32_min_value;

    if (src_known && dst_known) {
        verifier_mark_reg32_known(dst_reg, var32_off.value);
        return;
    }

    /* We get our maximum from the var_off, and our minimum is the
     * maximum of the operands' minima
     */
    dst_reg->u32_min_value = max(dst_reg->u32_min_value, umin_val);
    dst_reg->u32_max_value = var32_off.value | var32_off.mask;
    if (dst_reg->s32_min_value < 0 || smin_val < 0) {
        /* Lose signed bounds when ORing negative numbers,
         * ain't nobody got time for that.
         */
        dst_reg->s32_min_value = S32_MIN;
        dst_reg->s32_max_value = S32_MAX;
    } else {
        /* ORing two positives gives a positive, so safe to
         * cast result into s64.
         */
        dst_reg->s32_min_value = dst_reg->u32_min_value;
        dst_reg->s32_max_value = dst_reg->u32_max_value;
    }
}

static void scalar_min_max_or(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    bool src_known = tnum_is_const(src_reg->var_off);
    bool dst_known = tnum_is_const(dst_reg->var_off);
    s64 smin_val = src_reg->smin_value;
    u64 umin_val = src_reg->umin_value;

    if (src_known && dst_known) {
        verifier_mark_reg_known(dst_reg, dst_reg->var_off.value);
        return;
    }

    /* We get our maximum from the var_off, and our minimum is the
     * maximum of the operands' minima
     */
    dst_reg->umin_value = max(dst_reg->umin_value, umin_val);
    dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask;
    if (dst_reg->smin_value < 0 || smin_val < 0) {
        /* Lose signed bounds when ORing negative numbers,
         * ain't nobody got time for that.
         */
        dst_reg->smin_value = S64_MIN;
        dst_reg->smax_value = S64_MAX;
    } else {
        /* ORing two positives gives a positive, so safe to
         * cast result into s64.
         */
        dst_reg->smin_value = dst_reg->umin_value;
        dst_reg->smax_value = dst_reg->umax_value;
    }
    /* We may learn something more from the var_off */
    verifier_update_reg_bounds(dst_reg);
}

static void scalar32_min_max_xor(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    bool src_known = tnum_subreg_is_const(src_reg->var_off);
    bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
    struct tnum var32_off = tnum_subreg(dst_reg->var_off);
    s32 smin_val = src_reg->s32_min_value;

    if (src_known && dst_known) {
        verifier_mark_reg32_known(dst_reg, var32_off.value);
        return;
    }

    /* We get both minimum and maximum from the var32_off. */
    dst_reg->u32_min_value = var32_off.value;
    dst_reg->u32_max_value = var32_off.value | var32_off.mask;

    if (dst_reg->s32_min_value >= 0 && smin_val >= 0) {
        /* XORing two positive sign numbers gives a positive,
         * so safe to cast u32 result into s32.
         */
        dst_reg->s32_min_value = dst_reg->u32_min_value;
        dst_reg->s32_max_value = dst_reg->u32_max_value;
    } else {
        dst_reg->s32_min_value = S32_MIN;
        dst_reg->s32_max_value = S32_MAX;
    }
}

static void scalar_min_max_xor(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    bool src_known = tnum_is_const(src_reg->var_off);
    bool dst_known = tnum_is_const(dst_reg->var_off);
    s64 smin_val = src_reg->smin_value;

    if (src_known && dst_known) {
        /* dst_reg->var_off.value has been updated earlier */
        verifier_mark_reg_known(dst_reg, dst_reg->var_off.value);
        return;
    }

    /* We get both minimum and maximum from the var_off. */
    dst_reg->umin_value = dst_reg->var_off.value;
    dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask;

    if (dst_reg->smin_value >= 0 && smin_val >= 0) {
        /* XORing two positive sign numbers gives a positive,
         * so safe to cast u64 result into s64.
         */
        dst_reg->smin_value = dst_reg->umin_value;
        dst_reg->smax_value = dst_reg->umax_value;
    } else {
        dst_reg->smin_value = S64_MIN;
        dst_reg->smax_value = S64_MAX;
    }

    verifier_update_reg_bounds(dst_reg);
}

static void __scalar32_min_max_lsh(struct bpf_reg_state *dst_reg, u64 umin_val, u64 umax_val)
{
    /* We lose all sign bit information (except what we can pick
     * up from var_off)
     */
    dst_reg->s32_min_value = S32_MIN;
    dst_reg->s32_max_value = S32_MAX;
    /* If we might shift our top bit out, then we know nothing */
    if (umax_val > VERIFIER_THIRTYONE || dst_reg->u32_max_value > 1ULL << (VERIFIER_THIRTYONE - umax_val)) {
        dst_reg->u32_min_value = 0;
        dst_reg->u32_max_value = U32_MAX;
    } else {
        dst_reg->u32_min_value <<= umin_val;
        dst_reg->u32_max_value <<= umax_val;
    }
}

static void scalar32_min_max_lsh(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    u32 umax_val = src_reg->u32_max_value;
    u32 umin_val = src_reg->u32_min_value;
    /* u32 alu operation will zext upper bits */
    struct tnum subreg = tnum_subreg(dst_reg->var_off);

    __scalar32_min_max_lsh(dst_reg, umin_val, umax_val);
    dst_reg->var_off = tnum_subreg(tnum_lshift(subreg, umin_val));
    /* Not required but being careful mark reg64 bounds as unknown so
     * that we are forced to pick them up from tnum and zext later and
     * if some path skips this step we are still safe.
     */
    verifier_mark_reg64_unbounded(dst_reg);
    verifier_update_reg32_bounds(dst_reg);
}

static void __scalar64_min_max_lsh(struct bpf_reg_state *dst_reg, u64 umin_val, u64 umax_val)
{
    /* Special case <<32 because it is a common compiler pattern to sign
     * extend subreg by doing <<32 s>>32. In this case if 32bit bounds are
     * positive we know this shift will also be positive so we can track
     * bounds correctly. Otherwise we lose all sign bit information except
     * what we can pick up from var_off. Perhaps we can generalize this
     * later to shifts of any length.
     */
    if (umin_val == 0x20 && umax_val == 0x20 && dst_reg->s32_max_value >= 0) {
        dst_reg->smax_value = (s64)dst_reg->s32_max_value << 0x20;
    } else {
        dst_reg->smax_value = S64_MAX;
    }

    if (umin_val == 0x20 && umax_val == 0x20 && dst_reg->s32_min_value >= 0) {
        dst_reg->smin_value = (s64)dst_reg->s32_min_value << 0x20;
    } else {
        dst_reg->smin_value = S64_MIN;
    }

    /* If we might shift our top bit out, then we know nothing */
    if (dst_reg->umax_value > 1ULL << (0x3f - umax_val)) {
        dst_reg->umin_value = 0;
        dst_reg->umax_value = U64_MAX;
    } else {
        dst_reg->umin_value <<= umin_val;
        dst_reg->umax_value <<= umax_val;
    }
}

static void scalar_min_max_lsh(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    u64 umax_val = src_reg->umax_value;
    u64 umin_val = src_reg->umin_value;

    /* scalar64 calc uses 32bit unshifted bounds so must be called first */
    __scalar64_min_max_lsh(dst_reg, umin_val, umax_val);
    __scalar32_min_max_lsh(dst_reg, umin_val, umax_val);

    dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val);
    /* We may learn something more from the var_off */
    verifier_update_reg_bounds(dst_reg);
}

static void scalar32_min_max_rsh(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    struct tnum subreg = tnum_subreg(dst_reg->var_off);
    u32 umax_val = src_reg->u32_max_value;
    u32 umin_val = src_reg->u32_min_value;

    /* BPF_RSH is an unsigned shift.  If the value in dst_reg might
     * be negative, then either:
     * 1) src_reg might be zero, so the sign bit of the result is
     *    unknown, so we lose our signed bounds
     * 2) it's known negative, thus the unsigned bounds capture the
     *    signed bounds
     * 3) the signed bounds cross zero, so they tell us nothing
     *    about the result
     * If the value in dst_reg is known nonnegative, then again the
     * unsigned bounts capture the signed bounds.
     * Thus, in all cases it suffices to blow away our signed bounds
     * and rely on inferring new ones from the unsigned bounds and
     * var_off of the result.
     */
    dst_reg->s32_min_value = S32_MIN;
    dst_reg->s32_max_value = S32_MAX;

    dst_reg->var_off = tnum_rshift(subreg, umin_val);
    dst_reg->u32_min_value >>= umax_val;
    dst_reg->u32_max_value >>= umin_val;

    verifier_mark_reg64_unbounded(dst_reg);
    verifier_update_reg32_bounds(dst_reg);
}

static void scalar_min_max_rsh(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    u64 umax_val = src_reg->umax_value;
    u64 umin_val = src_reg->umin_value;

    /* BPF_RSH is an unsigned shift.  If the value in dst_reg might
     * be negative, then either:
     * 1) src_reg might be zero, so the sign bit of the result is
     *    unknown, so we lose our signed bounds
     * 2) it's known negative, thus the unsigned bounds capture the
     *    signed bounds
     * 3) the signed bounds cross zero, so they tell us nothing
     *    about the result
     * If the value in dst_reg is known nonnegative, then again the
     * unsigned bounts capture the signed bounds.
     * Thus, in all cases it suffices to blow away our signed bounds
     * and rely on inferring new ones from the unsigned bounds and
     * var_off of the result.
     */
    dst_reg->smin_value = S64_MIN;
    dst_reg->smax_value = S64_MAX;
    dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val);
    dst_reg->umin_value >>= umax_val;
    dst_reg->umax_value >>= umin_val;

    /* Its not easy to operate on alu32 bounds here because it depends
     * on bits being shifted in. Take easy way out and mark unbounded
     * so we can recalculate later from tnum.
     */
    verifier_mark_reg32_unbounded(dst_reg);
    verifier_update_reg_bounds(dst_reg);
}

static void scalar32_min_max_arsh(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    u64 umin_val = src_reg->u32_min_value;

    /* Upon reaching here, src_known is true and
     * umax_val is equal to umin_val.
     */
    dst_reg->s32_min_value = (u32)(((s32)dst_reg->s32_min_value) >> umin_val);
    dst_reg->s32_max_value = (u32)(((s32)dst_reg->s32_max_value) >> umin_val);

    dst_reg->var_off = tnum_arshift(tnum_subreg(dst_reg->var_off), umin_val, 0x20);

    /* blow away the dst_reg umin_value/umax_value and rely on
     * dst_reg var_off to refine the result.
     */
    dst_reg->u32_min_value = 0;
    dst_reg->u32_max_value = U32_MAX;

    verifier_mark_reg64_unbounded(dst_reg);
    verifier_update_reg32_bounds(dst_reg);
}

static void scalar_min_max_arsh(struct bpf_reg_state *dst_reg, struct bpf_reg_state *src_reg)
{
    u64 umin_val = src_reg->umin_value;

    /* Upon reaching here, src_known is true and umax_val is equal
     * to umin_val.
     */
    dst_reg->smin_value >>= umin_val;
    dst_reg->smax_value >>= umin_val;

    dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val, 0x40);

    /* blow away the dst_reg umin_value/umax_value and rely on
     * dst_reg var_off to refine the result.
     */
    dst_reg->umin_value = 0;
    dst_reg->umax_value = U64_MAX;

    /* Its not easy to operate on alu32 bounds here because it depends
     * on bits being shifted in from upper 32-bits. Take easy way out
     * and mark unbounded so we can recalculate later from tnum.
     */
    verifier_mark_reg32_unbounded(dst_reg);
    verifier_update_reg_bounds(dst_reg);
}

/* WARNING: This function does calculations on 64-bit values, but the actual
 * execution may occur on 32-bit values. Therefore, things like bitshifts
 * need extra checks in the 32-bit case.
 */
static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, struct bpf_insn *insn,
                                      struct bpf_reg_state *dst_reg, struct bpf_reg_state src_reg)
{
    struct bpf_reg_state *regs = cur_regs(env);
    u8 opcode = BPF_OP(insn->code);
    bool src_known;
    s64 smin_val, smax_val;
    u64 umin_val, umax_val;
    s32 s32_min_val, s32_max_val;
    u32 u32_min_val, u32_max_val;
    u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? VERIFIER_SIXTYFOUR : VERIFIER_THIRTYTWO;
    bool alu32 = (BPF_CLASS(insn->code) != BPF_ALU64);
    int ret;

    smin_val = src_reg.smin_value;
    smax_val = src_reg.smax_value;
    umin_val = src_reg.umin_value;
    umax_val = src_reg.umax_value;

    s32_min_val = src_reg.s32_min_value;
    s32_max_val = src_reg.s32_max_value;
    u32_min_val = src_reg.u32_min_value;
    u32_max_val = src_reg.u32_max_value;

    if (alu32) {
        src_known = tnum_subreg_is_const(src_reg.var_off);
        if ((src_known && (s32_min_val != s32_max_val || u32_min_val != u32_max_val)) || s32_min_val > s32_max_val ||
            u32_min_val > u32_max_val) {
            /* Taint dst register if offset had invalid bounds
             * derived from e.g. dead branches.
             */
            __mark_reg_unknown(env, dst_reg);
            return 0;
        }
    } else {
        src_known = tnum_is_const(src_reg.var_off);
        if ((src_known && (smin_val != smax_val || umin_val != umax_val)) || smin_val > smax_val ||
            umin_val > umax_val) {
            /* Taint dst register if offset had invalid bounds
             * derived from e.g. dead branches.
             */
            __mark_reg_unknown(env, dst_reg);
            return 0;
        }
    }

    if (!src_known && opcode != BPF_ADD && opcode != BPF_SUB && opcode != BPF_AND) {
        __mark_reg_unknown(env, dst_reg);
        return 0;
    }

    if (sanitize_needed(opcode)) {
        ret = sanitize_val_alu(env, insn);
        if (ret < 0) {
            return sanitize_err(env, insn, ret, NULL, NULL);
        }
    }

    /* Calculate sign/unsigned bounds and tnum for alu32 and alu64 bit ops.
     * There are two classes of instructions: The first class we track both
     * alu32 and alu64 sign/unsigned bounds independently this provides the
     * greatest amount of precision when alu operations are mixed with jmp32
     * operations. These operations are BPF_ADD, BPF_SUB, BPF_MUL, BPF_ADD,
     * and BPF_OR. This is possible because these ops have fairly easy to
     * understand and calculate behavior in both 32-bit and 64-bit alu ops.
     * See alu32 verifier tests for examples. The second class of
     * operations, BPF_LSH, BPF_RSH, and BPF_ARSH, however are not so easy
     * with regards to tracking sign/unsigned bounds because the bits may
     * cross subreg boundaries in the alu64 case. When this happens we mark
     * the reg unbounded in the subreg bound space and use the resulting
     * tnum to calculate an approximation of the sign/unsigned bounds.
     */
    switch (opcode) {
        case BPF_ADD:
            scalar32_min_max_add(dst_reg, &src_reg);
            scalar_min_max_add(dst_reg, &src_reg);
            dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off);
            break;
        case BPF_SUB:
            scalar32_min_max_sub(dst_reg, &src_reg);
            scalar_min_max_sub(dst_reg, &src_reg);
            dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg.var_off);
            break;
        case BPF_MUL:
            dst_reg->var_off = tnum_mul(dst_reg->var_off, src_reg.var_off);
            scalar32_min_max_mul(dst_reg, &src_reg);
            scalar_min_max_mul(dst_reg, &src_reg);
            break;
        case BPF_AND:
            dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg.var_off);
            scalar32_min_max_and(dst_reg, &src_reg);
            scalar_min_max_and(dst_reg, &src_reg);
            break;
        case BPF_OR:
            dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg.var_off);
            scalar32_min_max_or(dst_reg, &src_reg);
            scalar_min_max_or(dst_reg, &src_reg);
            break;
        case BPF_XOR:
            dst_reg->var_off = tnum_xor(dst_reg->var_off, src_reg.var_off);
            scalar32_min_max_xor(dst_reg, &src_reg);
            scalar_min_max_xor(dst_reg, &src_reg);
            break;
        case BPF_LSH:
            if (umax_val >= insn_bitness) {
                /* Shifts greater than 31 or 63 are undefined.
                 * This includes shifts by a negative number.
                 */
                mark_reg_unknown(env, regs, insn->dst_reg);
                break;
            }
            if (alu32) {
                scalar32_min_max_lsh(dst_reg, &src_reg);
            } else {
                scalar_min_max_lsh(dst_reg, &src_reg);
            }
            break;
        case BPF_RSH:
            if (umax_val >= insn_bitness) {
                /* Shifts greater than 31 or 63 are undefined.
                 * This includes shifts by a negative number.
                 */
                mark_reg_unknown(env, regs, insn->dst_reg);
                break;
            }
            if (alu32) {
                scalar32_min_max_rsh(dst_reg, &src_reg);
            } else {
                scalar_min_max_rsh(dst_reg, &src_reg);
            }
            break;
        case BPF_ARSH:
            if (umax_val >= insn_bitness) {
                /* Shifts greater than 31 or 63 are undefined.
                 * This includes shifts by a negative number.
                 */
                mark_reg_unknown(env, regs, insn->dst_reg);
                break;
            }
            if (alu32) {
                scalar32_min_max_arsh(dst_reg, &src_reg);
            } else {
                scalar_min_max_arsh(dst_reg, &src_reg);
            }
            break;
        default:
            mark_reg_unknown(env, regs, insn->dst_reg);
            break;
    }

    /* ALU32 ops are zero extended into 64bit register */
    if (alu32) {
        zext_32_to_64(dst_reg);
    }

    reg_bounds_sync(dst_reg);
    return 0;
}

/* Handles ALU ops other than BPF_END, BPF_NEG and BPF_MOV: computes new min/max
 * and var_off.
 */
static int adjust_reg_min_max_vals(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
    struct bpf_verifier_state *vstate = env->cur_state;
    struct bpf_func_state *state = vstate->frame[vstate->curframe];
    struct bpf_reg_state *regs = state->regs, *dst_reg, *src_reg;
    struct bpf_reg_state *ptr_reg = NULL, off_reg = {0};
    u8 opcode = BPF_OP(insn->code);
    int err;

    dst_reg = &regs[insn->dst_reg];
    src_reg = NULL;
    if (dst_reg->type != SCALAR_VALUE) {
        ptr_reg = dst_reg;
    } else {
        /* Make sure ID is cleared otherwise dst_reg min/max could be
         * incorrectly propagated into other registers by find_equal_scalars()
         */
        dst_reg->id = 0;
    }
    if (BPF_SRC(insn->code) == BPF_X) {
        src_reg = &regs[insn->src_reg];
        if (src_reg->type != SCALAR_VALUE) {
            if (dst_reg->type != SCALAR_VALUE) {
                /* Combining two pointers by any ALU op yields
                 * an arbitrary scalar. Disallow all math except
                 * pointer subtraction
                 */
                if (opcode == BPF_SUB && env->allow_ptr_leaks) {
                    mark_reg_unknown(env, regs, insn->dst_reg);
                    return 0;
                }
                verbose(env, "R%d pointer %s pointer prohibited\n", insn->dst_reg,
                        bpf_alu_string[opcode >> VERIFIER_FOUR]);
                return -EACCES;
            } else {
                /* scalar += pointer
                 * This is legal, but we have to reverse our
                 * src/dest handling in computing the range
                 */
                err = mark_chain_precision(env, insn->dst_reg);
                if (err) {
                    return err;
                }
                return adjust_ptr_min_max_vals(env, insn, src_reg, dst_reg);
            }
        } else if (ptr_reg) {
            /* pointer += scalar */
            err = mark_chain_precision(env, insn->src_reg);
            if (err) {
                return err;
            }
            return adjust_ptr_min_max_vals(env, insn, dst_reg, src_reg);
        }
    } else {
        /* Pretend the src is a reg with a known value, since we only
         * need to be able to read from this state.
         */
        off_reg.type = SCALAR_VALUE;
        verifier_mark_reg_known(&off_reg, insn->imm);
        src_reg = &off_reg;
        if (ptr_reg) { /* pointer += K */
            return adjust_ptr_min_max_vals(env, insn, ptr_reg, src_reg);
        }
    }

    /* Got here implies adding two SCALAR_VALUEs */
    if (WARN_ON_ONCE(ptr_reg)) {
        print_verifier_state(env, state);
        verbose(env, "verifier internal error: unexpected ptr_reg\n");
        return -EINVAL;
    }
    if (WARN_ON(!src_reg)) {
        print_verifier_state(env, state);
        verbose(env, "verifier internal error: no src_reg\n");
        return -EINVAL;
    }
    return adjust_scalar_min_max_vals(env, insn, dst_reg, *src_reg);
}

/* check validity of 32-bit and 64-bit arithmetic operations */
static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
    struct bpf_reg_state *regs = cur_regs(env);
    u8 opcode = BPF_OP(insn->code);
    int err;

    if (opcode == BPF_END || opcode == BPF_NEG) {
        if (opcode == BPF_NEG) {
            if (BPF_SRC(insn->code) != 0 || insn->src_reg != BPF_REG_0 || insn->off != 0 || insn->imm != 0) {
                verbose(env, "BPF_NEG uses reserved fields\n");
                return -EINVAL;
            }
        } else {
            if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
                (insn->imm != 0x10 && insn->imm != VERIFIER_THIRTYTWO && insn->imm != VERIFIER_SIXTYFOUR) ||
                BPF_CLASS(insn->code) == BPF_ALU64) {
                verbose(env, "BPF_END uses reserved fields\n");
                return -EINVAL;
            }
        }

        /* check src operand */
        err = check_reg_arg(env, insn->dst_reg, SRC_OP);
        if (err) {
            return err;
        }

        if (is_pointer_value(env, insn->dst_reg)) {
            verbose(env, "R%d pointer arithmetic prohibited\n", insn->dst_reg);
            return -EACCES;
        }

        /* check dest operand */
        err = check_reg_arg(env, insn->dst_reg, DST_OP);
        if (err) {
            return err;
        }
    } else if (opcode == BPF_MOV) {
        if (BPF_SRC(insn->code) == BPF_X) {
            if (insn->imm != 0 || insn->off != 0) {
                verbose(env, "BPF_MOV uses reserved fields\n");
                return -EINVAL;
            }
            /* check src operand */
            err = check_reg_arg(env, insn->src_reg, SRC_OP);
            if (err) {
                return err;
            }
        } else {
            if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
                verbose(env, "BPF_MOV uses reserved fields\n");
                return -EINVAL;
            }
        }

        /* check dest operand, mark as required later */
        err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
        if (err) {
            return err;
        }

        if (BPF_SRC(insn->code) == BPF_X) {
            struct bpf_reg_state *src_reg = regs + insn->src_reg;
            struct bpf_reg_state *dst_reg = regs + insn->dst_reg;

            if (BPF_CLASS(insn->code) == BPF_ALU64) {
                /* case: R1 = R2
                 * copy register state to dest reg
                 */
                if (src_reg->type == SCALAR_VALUE && !src_reg->id) {
                    /* Assign src and dst registers the same ID
                     * that will be used by find_equal_scalars()
                     * to propagate min/max range.
                     */
                    src_reg->id = ++env->id_gen;
                }
                *dst_reg = *src_reg;
                dst_reg->live |= REG_LIVE_WRITTEN;
                dst_reg->subreg_def = DEF_NOT_SUBREG;
            } else {
                /* R1 = (u32) R2 */
                if (is_pointer_value(env, insn->src_reg)) {
                    verbose(env, "R%d partial copy of pointer\n", insn->src_reg);
                    return -EACCES;
                } else if (src_reg->type == SCALAR_VALUE) {
                    *dst_reg = *src_reg;
                    /* Make sure ID is cleared otherwise
                     * dst_reg min/max could be incorrectly
                     * propagated into src_reg by find_equal_scalars()
                     */
                    dst_reg->id = 0;
                    dst_reg->live |= REG_LIVE_WRITTEN;
                    dst_reg->subreg_def = env->insn_idx + 1;
                } else {
                    mark_reg_unknown(env, regs, insn->dst_reg);
                }
                zext_32_to_64(dst_reg);

                reg_bounds_sync(dst_reg);
            }
        } else {
            /* case: R = imm
             * remember the value we stored into this reg
             */
            /* clear any state __mark_reg_known doesn't set */
            mark_reg_unknown(env, regs, insn->dst_reg);
            regs[insn->dst_reg].type = SCALAR_VALUE;
            if (BPF_CLASS(insn->code) == BPF_ALU64) {
                verifier_mark_reg_known(regs + insn->dst_reg, insn->imm);
            } else {
                verifier_mark_reg_known(regs + insn->dst_reg, (u32)insn->imm);
            }
        }
    } else if (opcode > BPF_END) {
        verbose(env, "invalid BPF_ALU opcode %x\n", opcode);
        return -EINVAL;
    } else { /* all other ALU ops: and, sub, xor, add, ... */
        if (BPF_SRC(insn->code) == BPF_X) {
            if (insn->imm != 0 || insn->off != 0) {
                verbose(env, "BPF_ALU uses reserved fields\n");
                return -EINVAL;
            }
            /* check src1 operand */
            err = check_reg_arg(env, insn->src_reg, SRC_OP);
            if (err) {
                return err;
            }
        } else {
            if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
                verbose(env, "BPF_ALU uses reserved fields\n");
                return -EINVAL;
            }
        }

        /* check src2 operand */
        err = check_reg_arg(env, insn->dst_reg, SRC_OP);
        if (err) {
            return err;
        }

        if ((opcode == BPF_MOD || opcode == BPF_DIV) && BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
            verbose(env, "div by zero\n");
            return -EINVAL;
        }

        if ((opcode == BPF_LSH || opcode == BPF_RSH || opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) {
            int size = BPF_CLASS(insn->code) == BPF_ALU64 ? VERIFIER_SIXTYFOUR : 32;
            if (insn->imm < 0 || insn->imm >= size) {
                verbose(env, "invalid shift %d\n", insn->imm);
                return -EINVAL;
            }
        }
        /* check dest operand */
        err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
        if (err) {
            return err;
        }
        return adjust_reg_min_max_vals(env, insn);
    }

    return 0;
}

static void __find_good_pkt_pointers(struct bpf_func_state *state, struct bpf_reg_state *dst_reg,
                                     enum bpf_reg_type type, u16 new_range)
{
    struct bpf_reg_state *reg;
    int i;

    for (i = 0; i < MAX_BPF_REG; i++) {
        reg = &state->regs[i];
        if (reg->type == type && reg->id == dst_reg->id) {
            /* keep the maximum range already checked */
            reg->range = max(reg->range, new_range);
        }
    }

    bpf_for_each_spilled_reg(i, state, reg)
    {
        if (!reg) {
            continue;
        }
        if (reg->type == type && reg->id == dst_reg->id) {
            reg->range = max(reg->range, new_range);
        }
    }
}

static void find_good_pkt_pointers(struct bpf_verifier_state *vstate, struct bpf_reg_state *dst_reg,
                                   enum bpf_reg_type type, bool range_right_open)
{
    u16 new_range;
    int i;

    if (dst_reg->off < 0 || (dst_reg->off == 0 && range_right_open)) {
        /* This doesn't give us any range */
        return;
    }

    if (dst_reg->umax_value > MAX_PACKET_OFF || dst_reg->umax_value + dst_reg->off > MAX_PACKET_OFF) {
        /* Risk of overflow.  For instance, ptr + (1<<63) may be less
         * than pkt_end, but that's because it's also less than pkt.
         */
        return;
    }

    new_range = dst_reg->off;
    if (range_right_open) {
        new_range--;
    }

    /* Examples for register markings:
     *
     * pkt_data in dst register:
     *
     *   r2 = r3;
     *   r2 += 8;
     *   if (r2 > pkt_end) goto <handle exception>
     *   <access okay>
     *
     *   r2 = r3;
     *   r2 += 8;
     *   if (r2 < pkt_end) goto <access okay>
     *   <handle exception>
     *
     *   Where:
     *     r2 == dst_reg, pkt_end == src_reg
     *     r2=pkt(id=n,off=8,r=0)
     *     r3=pkt(id=n,off=0,r=0)
     *
     * pkt_data in src register:
     *
     *   r2 = r3;
     *   r2 += 8;
     *   if (pkt_end >= r2) goto <access okay>
     *   <handle exception>
     *
     *   r2 = r3;
     *   r2 += 8;
     *   if (pkt_end <= r2) goto <handle exception>
     *   <access okay>
     *
     *   Where:
     *     pkt_end == dst_reg, r2 == src_reg
     *     r2=pkt(id=n,off=8,r=0)
     *     r3=pkt(id=n,off=0,r=0)
     *
     * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
     * or r3=pkt(id=n,off=0,r=8-1), so that range of bytes [r3, r3 + 8)
     * and [r3, r3 + 8-1) respectively is safe to access depending on
     * the check.
     */

    /* If our ids match, then we must have the same max_value.  And we
     * don't care about the other reg's fixed offset, since if it's too big
     * the range won't allow anything.
     * dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16.
     */
    for (i = 0; i <= vstate->curframe; i++) {
        __find_good_pkt_pointers(vstate->frame[i], dst_reg, type, new_range);
    }
}

static int is_branch32_taken(struct bpf_reg_state *reg, u32 val, u8 opcode)
{
    struct tnum subreg = tnum_subreg(reg->var_off);
    s32 sval = (s32)val;

    switch (opcode) {
        case BPF_JEQ:
            if (tnum_is_const(subreg)) {
                return !!tnum_equals_const(subreg, val);
            }
            break;
        case BPF_JNE:
            if (tnum_is_const(subreg)) {
                return !tnum_equals_const(subreg, val);
            }
            break;
        case BPF_JSET:
            if ((~subreg.mask & subreg.value) & val) {
                return 1;
            }
            if (!((subreg.mask | subreg.value) & val)) {
                return 0;
            }
            break;
        case BPF_JGT:
            if (reg->u32_min_value > val) {
                return 1;
            } else if (reg->u32_max_value <= val) {
                return 0;
            }
            break;
        case BPF_JSGT:
            if (reg->s32_min_value > sval) {
                return 1;
            } else if (reg->s32_max_value <= sval) {
                return 0;
            }
            break;
        case BPF_JLT:
            if (reg->u32_max_value < val) {
                return 1;
            } else if (reg->u32_min_value >= val) {
                return 0;
            }
            break;
        case BPF_JSLT:
            if (reg->s32_max_value < sval) {
                return 1;
            } else if (reg->s32_min_value >= sval) {
                return 0;
            }
            break;
        case BPF_JGE:
            if (reg->u32_min_value >= val) {
                return 1;
            } else if (reg->u32_max_value < val) {
                return 0;
            }
            break;
        case BPF_JSGE:
            if (reg->s32_min_value >= sval) {
                return 1;
            } else if (reg->s32_max_value < sval) {
                return 0;
            }
            break;
        case BPF_JLE:
            if (reg->u32_max_value <= val) {
                return 1;
            } else if (reg->u32_min_value > val) {
                return 0;
            }
            break;
        case BPF_JSLE:
            if (reg->s32_max_value <= sval) {
                return 1;
            } else if (reg->s32_min_value > sval) {
                return 0;
            }
            break;
    }

    return -1;
}

static int is_branch64_taken(struct bpf_reg_state *reg, u64 val, u8 opcode)
{
    s64 sval = (s64)val;

    switch (opcode) {
        case BPF_JEQ:
            if (tnum_is_const(reg->var_off)) {
                return !!tnum_equals_const(reg->var_off, val);
            }
            break;
        case BPF_JNE:
            if (tnum_is_const(reg->var_off)) {
                return !tnum_equals_const(reg->var_off, val);
            }
            break;
        case BPF_JSET:
            if ((~reg->var_off.mask & reg->var_off.value) & val) {
                return 1;
            }
            if (!((reg->var_off.mask | reg->var_off.value) & val)) {
                return 0;
            }
            break;
        case BPF_JGT:
            if (reg->umin_value > val) {
                return 1;
            } else if (reg->umax_value <= val) {
                return 0;
            }
            break;
        case BPF_JSGT:
            if (reg->smin_value > sval) {
                return 1;
            } else if (reg->smax_value <= sval) {
                return 0;
            }
            break;
        case BPF_JLT:
            if (reg->umax_value < val) {
                return 1;
            } else if (reg->umin_value >= val) {
                return 0;
            }
            break;
        case BPF_JSLT:
            if (reg->smax_value < sval) {
                return 1;
            } else if (reg->smin_value >= sval) {
                return 0;
            }
            break;
        case BPF_JGE:
            if (reg->umin_value >= val) {
                return 1;
            } else if (reg->umax_value < val) {
                return 0;
            }
            break;
        case BPF_JSGE:
            if (reg->smin_value >= sval) {
                return 1;
            } else if (reg->smax_value < sval) {
                return 0;
            }
            break;
        case BPF_JLE:
            if (reg->umax_value <= val) {
                return 1;
            } else if (reg->umin_value > val) {
                return 0;
            }
            break;
        case BPF_JSLE:
            if (reg->smax_value <= sval) {
                return 1;
            } else if (reg->smin_value > sval) {
                return 0;
            }
            break;
    }

    return -1;
}

/* compute branch direction of the expression "if (reg opcode val) goto target;"
 * and return:
 *  1 - branch will be taken and "goto target" will be executed
 *  0 - branch will not be taken and fall-through to next insn
 * -1 - unknown. Example: "if (reg < 5)" is unknown when register value
 *      range [0,10]
 */
static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode, bool is_jmp32)
{
    if (__is_pointer_value(false, reg)) {
        if (!reg_type_not_null(reg->type)) {
            return -1;
        }

        /* If pointer is valid tests against zero will fail so we can
         * use this to direct branch taken.
         */
        if (val != 0) {
            return -1;
        }

        switch (opcode) {
            case BPF_JEQ:
                return 0;
            case BPF_JNE:
                return 1;
            default:
                return -1;
        }
    }

    if (is_jmp32) {
        return is_branch32_taken(reg, val, opcode);
    }
    return is_branch64_taken(reg, val, opcode);
}

/* Adjusts the register min/max values in the case that the dst_reg is the
 * variable register that we are working on, and src_reg is a constant or we're
 * simply doing a BPF_K check.
 * In JEQ/JNE cases we also adjust the var_off values.
 */
static void reg_set_min_max(struct bpf_reg_state *true_reg, struct bpf_reg_state *false_reg, u64 val, u32 val32,
                            u8 opcode, bool is_jmp32)
{
    struct tnum false_32off = tnum_subreg(false_reg->var_off);
    struct tnum false_64off = false_reg->var_off;
    struct tnum true_32off = tnum_subreg(true_reg->var_off);
    struct tnum true_64off = true_reg->var_off;
    s64 sval = (s64)val;
    s32 sval32 = (s32)val32;

    /* If the dst_reg is a pointer, we can't learn anything about its
     * variable offset from the compare (unless src_reg were a pointer into
     * the same object, but we don't bother with that.
     * Since false_reg and true_reg have the same type by construction, we
     * only need to check one of them for pointerness.
     */
    if (__is_pointer_value(false, false_reg)) {
        return;
    }

    switch (opcode) {
    /* JEQ/JNE comparison doesn't change the register equivalence.
     *
     * r1 = r2;
     * if (r1 == 42) goto label;
     * ...
     * label: // here both r1 and r2 are known to be 42.
     *
     * Hence when marking register as known preserve it's ID.
     */
        case BPF_JEQ:
            if (is_jmp32) {
                __mark_reg32_known(true_reg, val32);
                true_32off = tnum_subreg(true_reg->var_off);
            } else {
                ___mark_reg_known(true_reg, val);
                true_64off = true_reg->var_off;
            }
            break;
        case BPF_JNE:
            if (is_jmp32) {
                __mark_reg32_known(false_reg, val32);
                false_32off = tnum_subreg(false_reg->var_off);
            } else {
                ___mark_reg_known(false_reg, val);
                false_64off = false_reg->var_off;
            }
            break;
        case BPF_JSET:
            if (is_jmp32) {
                false_32off = tnum_and(false_32off, tnum_const(~val32));
                if (is_power_of_2(val32)) {
                    true_32off = tnum_or(true_32off, tnum_const(val32));
                }
            } else {
                false_64off = tnum_and(false_64off, tnum_const(~val));
                if (is_power_of_2(val)) {
                    true_64off = tnum_or(true_64off, tnum_const(val));
                }
            }
            break;
        case BPF_JGE:
        case BPF_JGT: {
            if (is_jmp32) {
                u32 false_umax = opcode == BPF_JGT ? val32 : val32 - 1;
                u32 true_umin = opcode == BPF_JGT ? val32 + 1 : val32;

                false_reg->u32_max_value = min(false_reg->u32_max_value, false_umax);
                true_reg->u32_min_value = max(true_reg->u32_min_value, true_umin);
            } else {
                u64 false_umax = opcode == BPF_JGT ? val : val - 1;
                u64 true_umin = opcode == BPF_JGT ? val + 1 : val;

                false_reg->umax_value = min(false_reg->umax_value, false_umax);
                true_reg->umin_value = max(true_reg->umin_value, true_umin);
            }
            break;
        }
        case BPF_JSGE:
        case BPF_JSGT: {
            if (is_jmp32) {
                s32 false_smax = opcode == BPF_JSGT ? sval32 : sval32 - 1;
                s32 true_smin = opcode == BPF_JSGT ? sval32 + 1 : sval32;

                false_reg->s32_max_value = min(false_reg->s32_max_value, false_smax);
                true_reg->s32_min_value = max(true_reg->s32_min_value, true_smin);
            } else {
                s64 false_smax = opcode == BPF_JSGT ? sval : sval - 1;
                s64 true_smin = opcode == BPF_JSGT ? sval + 1 : sval;

                false_reg->smax_value = min(false_reg->smax_value, false_smax);
                true_reg->smin_value = max(true_reg->smin_value, true_smin);
            }
            break;
        }
        case BPF_JLE:
        case BPF_JLT: {
            if (is_jmp32) {
                u32 false_umin = opcode == BPF_JLT ? val32 : val32 + 1;
                u32 true_umax = opcode == BPF_JLT ? val32 - 1 : val32;

                false_reg->u32_min_value = max(false_reg->u32_min_value, false_umin);
                true_reg->u32_max_value = min(true_reg->u32_max_value, true_umax);
            } else {
                u64 false_umin = opcode == BPF_JLT ? val : val + 1;
                u64 true_umax = opcode == BPF_JLT ? val - 1 : val;

                false_reg->umin_value = max(false_reg->umin_value, false_umin);
                true_reg->umax_value = min(true_reg->umax_value, true_umax);
            }
            break;
        }
        case BPF_JSLE:
        case BPF_JSLT: {
            if (is_jmp32) {
                s32 false_smin = opcode == BPF_JSLT ? sval32 : sval32 + 1;
                s32 true_smax = opcode == BPF_JSLT ? sval32 - 1 : sval32;

                false_reg->s32_min_value = max(false_reg->s32_min_value, false_smin);
                true_reg->s32_max_value = min(true_reg->s32_max_value, true_smax);
            } else {
                s64 false_smin = opcode == BPF_JSLT ? sval : sval + 1;
                s64 true_smax = opcode == BPF_JSLT ? sval - 1 : sval;

                false_reg->smin_value = max(false_reg->smin_value, false_smin);
                true_reg->smax_value = min(true_reg->smax_value, true_smax);
            }
            break;
        }
        default:
            return;
    }

    if (is_jmp32) {
        false_reg->var_off = tnum_or(tnum_clear_subreg(false_64off), tnum_subreg(false_32off));
        true_reg->var_off = tnum_or(tnum_clear_subreg(true_64off), tnum_subreg(true_32off));
        verifier_reg_combine_32_into_64(false_reg);
        verifier_reg_combine_32_into_64(true_reg);
    } else {
        false_reg->var_off = false_64off;
        true_reg->var_off = true_64off;
        __reg_combine_64_into_32(false_reg);
        __reg_combine_64_into_32(true_reg);
    }
}

/* Same as above, but for the case that dst_reg holds a constant and src_reg is
 * the variable reg.
 */
static void reg_set_min_max_inv(struct bpf_reg_state *true_reg, struct bpf_reg_state *false_reg, u64 val, u32 val32,
                                u8 opcode, bool is_jmp32)
{
    /* How can we transform "a <op> b" into "b <op> a"? */
    static const u8 opcode_flip[VERIFIER_SIXTEEN] = {
        [BPF_JEQ >> VERIFIER_FOUR] = BPF_JEQ,
        [BPF_JNE >> VERIFIER_FOUR] = BPF_JNE,
        [BPF_JSET >> VERIFIER_FOUR] = BPF_JSET,
        /* these swap "lesser" and "greater" (L and G in the opcodes) */
        [BPF_JGE >> VERIFIER_FOUR] = BPF_JLE,
        [BPF_JGT >> VERIFIER_FOUR] = BPF_JLT,
        [BPF_JLE >> VERIFIER_FOUR] = BPF_JGE,
        [BPF_JLT >> VERIFIER_FOUR] = BPF_JGT,
        [BPF_JSGE >> VERIFIER_FOUR] = BPF_JSLE,
        [BPF_JSGT >> VERIFIER_FOUR] = BPF_JSLT,
        [BPF_JSLE >> VERIFIER_FOUR] = BPF_JSGE,
        [BPF_JSLT >> VERIFIER_FOUR] = BPF_JSGT};
    opcode = opcode_flip[opcode >> VERIFIER_FOUR];
    /* This uses zero as "not present in table"; luckily the zero opcode,
     * BPF_JA, can't get here.
     */
    if (opcode) {
        reg_set_min_max(true_reg, false_reg, val, val32, opcode, is_jmp32);
    }
}

/* Regs are known to be equal, so intersect their min/max/var_off */
static void __reg_combine_min_max(struct bpf_reg_state *src_reg, struct bpf_reg_state *dst_reg)
{
    src_reg->umin_value = dst_reg->umin_value = max(src_reg->umin_value, dst_reg->umin_value);
    src_reg->umax_value = dst_reg->umax_value = min(src_reg->umax_value, dst_reg->umax_value);
    src_reg->smin_value = dst_reg->smin_value = max(src_reg->smin_value, dst_reg->smin_value);
    src_reg->smax_value = dst_reg->smax_value = min(src_reg->smax_value, dst_reg->smax_value);
    src_reg->var_off = dst_reg->var_off = tnum_intersect(src_reg->var_off, dst_reg->var_off);
    /* We might have learned new bounds from the var_off. */
    reg_bounds_sync(src_reg);
    reg_bounds_sync(dst_reg);
}

static void reg_combine_min_max(struct bpf_reg_state *true_src, struct bpf_reg_state *true_dst,
                                struct bpf_reg_state *false_src, struct bpf_reg_state *false_dst, u8 opcode)
{
    switch (opcode) {
        case BPF_JEQ:
            __reg_combine_min_max(true_src, true_dst);
            break;
        case BPF_JNE:
            __reg_combine_min_max(false_src, false_dst);
            break;
    }
}

static void mark_ptr_or_null_reg(struct bpf_func_state *state, struct bpf_reg_state *reg, u32 id, bool is_null)
{
    if (type_may_be_null(reg->type) && reg->id == id &&
        !WARN_ON_ONCE(!reg->id)) {
        if (WARN_ON_ONCE(reg->smin_value || reg->smax_value ||
            !tnum_equals_const(reg->var_off, 0) || reg->off)) {
            /* Old offset (both fixed and variable parts) should
             * have been known-zero, because we don't allow pointer
             * arithmetic on pointers that might be NULL. If we
             * see this happening, don't convert the register.
             */
            return;
        }
        if (is_null) {
            reg->type = SCALAR_VALUE;
        } else if (base_type(reg->type) == PTR_TO_MAP_VALUE) {
            const struct bpf_map *map = reg->map_ptr;

            if (map->inner_map_meta) {
                reg->type = CONST_PTR_TO_MAP;
                reg->map_ptr = map->inner_map_meta;
            } else if (map->map_type == BPF_MAP_TYPE_XSKMAP) {
                reg->type = PTR_TO_XDP_SOCK;
            } else if (map->map_type == BPF_MAP_TYPE_SOCKMAP || map->map_type == BPF_MAP_TYPE_SOCKHASH) {
                reg->type = PTR_TO_SOCKET;
            } else {
                reg->type = PTR_TO_MAP_VALUE;
            }
        } else {
            reg->type &= ~PTR_MAYBE_NULL;
        }

        if (is_null) {
            /* We don't need id and ref_obj_id from this point
             * onwards anymore, thus we should better reset it,
             * so that state pruning has chances to take effect.
             */
            reg->id = 0;
            reg->ref_obj_id = 0;
        } else if (!reg_may_point_to_spin_lock(reg)) {
            /* For not-NULL ptr, reg->ref_obj_id will be reset
             * in release_reg_references().
             *
             * reg->id is still used by spin_lock ptr. Other
             * than spin_lock ptr type, reg->id can be reset.
             */
            reg->id = 0;
        }
    }
}

static void __mark_ptr_or_null_regs(struct bpf_func_state *state, u32 id, bool is_null)
{
    struct bpf_reg_state *reg;
    int i;

    for (i = 0; i < MAX_BPF_REG; i++) {
        mark_ptr_or_null_reg(state, &state->regs[i], id, is_null);
    }

    bpf_for_each_spilled_reg(i, state, reg)
    {
        if (!reg) {
            continue;
        }
        mark_ptr_or_null_reg(state, reg, id, is_null);
    }
}

/* The logic is similar to find_good_pkt_pointers(), both could eventually
 * be folded together at some point.
 */
static void mark_ptr_or_null_regs(struct bpf_verifier_state *vstate, u32 regno, bool is_null)
{
    struct bpf_func_state *state = vstate->frame[vstate->curframe];
    struct bpf_reg_state *regs = state->regs;
    u32 ref_obj_id = regs[regno].ref_obj_id;
    u32 id = regs[regno].id;
    int i;

    if (ref_obj_id && ref_obj_id == id && is_null) {
        /* regs[regno] is in the " == NULL" branch.
         * No one could have freed the reference state before
         * doing the NULL check.
         */
        WARN_ON_ONCE(release_reference_state(state, id));
    }

    for (i = 0; i <= vstate->curframe; i++) {
        __mark_ptr_or_null_regs(vstate->frame[i], id, is_null);
    }
}

static bool try_match_pkt_pointers(const struct bpf_insn *insn, struct bpf_reg_state *dst_reg,
                                   struct bpf_reg_state *src_reg, struct bpf_verifier_state *this_branch,
                                   struct bpf_verifier_state *other_branch)
{
    if (BPF_SRC(insn->code) != BPF_X) {
        return false;
    }

    /* Pointers are always 64-bit. */
    if (BPF_CLASS(insn->code) == BPF_JMP32) {
        return false;
    }

    switch (BPF_OP(insn->code)) {
        case BPF_JGT:
            if ((dst_reg->type == PTR_TO_PACKET && src_reg->type == PTR_TO_PACKET_END) ||
                (dst_reg->type == PTR_TO_PACKET_META && reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
                /* pkt_data' > pkt_end, pkt_meta' > pkt_data */
                find_good_pkt_pointers(this_branch, dst_reg, dst_reg->type, false);
            } else if ((dst_reg->type == PTR_TO_PACKET_END && src_reg->type == PTR_TO_PACKET) ||
                       (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && src_reg->type == PTR_TO_PACKET_META)) {
                /* pkt_end > pkt_data', pkt_data > pkt_meta' */
                find_good_pkt_pointers(other_branch, src_reg, src_reg->type, true);
            } else {
                return false;
            }
            break;
        case BPF_JLT:
            if ((dst_reg->type == PTR_TO_PACKET && src_reg->type == PTR_TO_PACKET_END) ||
                (dst_reg->type == PTR_TO_PACKET_META && reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
                /* pkt_data' < pkt_end, pkt_meta' < pkt_data */
                find_good_pkt_pointers(other_branch, dst_reg, dst_reg->type, true);
            } else if ((dst_reg->type == PTR_TO_PACKET_END && src_reg->type == PTR_TO_PACKET) ||
                       (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && src_reg->type == PTR_TO_PACKET_META)) {
                /* pkt_end < pkt_data', pkt_data > pkt_meta' */
                find_good_pkt_pointers(this_branch, src_reg, src_reg->type, false);
            } else {
                return false;
            }
            break;
        case BPF_JGE:
            if ((dst_reg->type == PTR_TO_PACKET && src_reg->type == PTR_TO_PACKET_END) ||
                (dst_reg->type == PTR_TO_PACKET_META && reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
                /* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */
                find_good_pkt_pointers(this_branch, dst_reg, dst_reg->type, true);
            } else if ((dst_reg->type == PTR_TO_PACKET_END && src_reg->type == PTR_TO_PACKET) ||
                       (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && src_reg->type == PTR_TO_PACKET_META)) {
                /* pkt_end >= pkt_data', pkt_data >= pkt_meta' */
                find_good_pkt_pointers(other_branch, src_reg, src_reg->type, false);
            } else {
                return false;
            }
            break;
        case BPF_JLE:
            if ((dst_reg->type == PTR_TO_PACKET && src_reg->type == PTR_TO_PACKET_END) ||
                (dst_reg->type == PTR_TO_PACKET_META && reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
                /* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */
                find_good_pkt_pointers(other_branch, dst_reg, dst_reg->type, false);
            } else if ((dst_reg->type == PTR_TO_PACKET_END && src_reg->type == PTR_TO_PACKET) ||
                       (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) && src_reg->type == PTR_TO_PACKET_META)) {
                /* pkt_end <= pkt_data', pkt_data <= pkt_meta' */
                find_good_pkt_pointers(this_branch, src_reg, src_reg->type, true);
            } else {
                return false;
            }
            break;
        default:
            return false;
    }

    return true;
}

static void find_equal_scalars(struct bpf_verifier_state *vstate, struct bpf_reg_state *known_reg)
{
    struct bpf_func_state *state;
    struct bpf_reg_state *reg;
    int i, j;

    for (i = 0; i <= vstate->curframe; i++) {
        state = vstate->frame[i];
        for (j = 0; j < MAX_BPF_REG; j++) {
            reg = &state->regs[j];
            if (reg->type == SCALAR_VALUE && reg->id == known_reg->id) {
                *reg = *known_reg;
            }
        }

        bpf_for_each_spilled_reg(j, state, reg)
        {
            if (!reg) {
                continue;
            }
            if (reg->type == SCALAR_VALUE && reg->id == known_reg->id) {
                *reg = *known_reg;
            }
        }
    }
}

static int check_cond_jmp_op(struct bpf_verifier_env *env, struct bpf_insn *insn, int *insn_idx)
{
    struct bpf_verifier_state *this_branch = env->cur_state;
    struct bpf_verifier_state *other_branch;
    struct bpf_reg_state *regs = this_branch->frame[this_branch->curframe]->regs;
    struct bpf_reg_state *dst_reg, *other_branch_regs, *src_reg = NULL;
    u8 opcode = BPF_OP(insn->code);
    bool is_jmp32;
    int pred = -1;
    int err;

    /* Only conditional jumps are expected to reach here. */
    if (opcode == BPF_JA || opcode > BPF_JSLE) {
        verbose(env, "invalid BPF_JMP/JMP32 opcode %x\n", opcode);
        return -EINVAL;
    }

    if (BPF_SRC(insn->code) == BPF_X) {
        if (insn->imm != 0) {
            verbose(env, "BPF_JMP/JMP32 uses reserved fields\n");
            return -EINVAL;
        }

        /* check src1 operand */
        err = check_reg_arg(env, insn->src_reg, SRC_OP);
        if (err) {
            return err;
        }

        if (is_pointer_value(env, insn->src_reg)) {
            verbose(env, "R%d pointer comparison prohibited\n", insn->src_reg);
            return -EACCES;
        }
        src_reg = &regs[insn->src_reg];
    } else {
        if (insn->src_reg != BPF_REG_0) {
            verbose(env, "BPF_JMP/JMP32 uses reserved fields\n");
            return -EINVAL;
        }
    }

    /* check src2 operand */
    err = check_reg_arg(env, insn->dst_reg, SRC_OP);
    if (err) {
        return err;
    }

    dst_reg = &regs[insn->dst_reg];
    is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;

    if (BPF_SRC(insn->code) == BPF_K) {
        pred = is_branch_taken(dst_reg, insn->imm, opcode, is_jmp32);
    } else if (src_reg->type == SCALAR_VALUE && is_jmp32 && tnum_is_const(tnum_subreg(src_reg->var_off))) {
        pred = is_branch_taken(dst_reg, tnum_subreg(src_reg->var_off).value, opcode, is_jmp32);
    } else if (src_reg->type == SCALAR_VALUE && !is_jmp32 && tnum_is_const(src_reg->var_off)) {
        pred = is_branch_taken(dst_reg, src_reg->var_off.value, opcode, is_jmp32);
    }

    if (pred >= 0) {
        /* If we get here with a dst_reg pointer type it is because
         * above is_branch_taken() special cased the 0 comparison.
         */
        if (!__is_pointer_value(false, dst_reg)) {
            err = mark_chain_precision(env, insn->dst_reg);
        }
        if (BPF_SRC(insn->code) == BPF_X && !err) {
            err = mark_chain_precision(env, insn->src_reg);
        }
        if (err) {
            return err;
        }
    }

    if (pred == 1) {
        /* Only follow the goto, ignore fall-through. If needed, push
         * the fall-through branch for simulation under speculative
         * execution.
         */
        if (!env->bypass_spec_v1 && !sanitize_speculative_path(env, insn, *insn_idx + 1, *insn_idx)) {
            return -EFAULT;
        }
        *insn_idx += insn->off;
        return 0;
    } else if (pred == 0) {
        /* Only follow the fall-through branch, since that's where the
         * program will go. If needed, push the goto branch for
         * simulation under speculative execution.
         */
        if (!env->bypass_spec_v1 && !sanitize_speculative_path(env, insn, *insn_idx + insn->off + 1, *insn_idx)) {
            return -EFAULT;
        }
        return 0;
    }

    other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx, false);
    if (!other_branch) {
        return -EFAULT;
    }
    other_branch_regs = other_branch->frame[other_branch->curframe]->regs;

    /* detect if we are comparing against a constant value so we can adjust
     * our min/max values for our dst register.
     * this is only legit if both are scalars (or pointers to the same
     * object, I suppose, but we don't support that right now), because
     * otherwise the different base pointers mean the offsets aren't
     * comparable.
     */
    if (BPF_SRC(insn->code) == BPF_X) {
        struct bpf_reg_state *src_reg_in = &regs[insn->src_reg];

        if (dst_reg->type == SCALAR_VALUE && src_reg_in->type == SCALAR_VALUE) {
            if (tnum_is_const(src_reg_in->var_off) || (is_jmp32 && tnum_is_const(tnum_subreg(src_reg_in->var_off)))) {
                reg_set_min_max(&other_branch_regs[insn->dst_reg], dst_reg, src_reg_in->var_off.value,
                                tnum_subreg(src_reg_in->var_off).value, opcode, is_jmp32);
            } else if (tnum_is_const(dst_reg->var_off) || (is_jmp32 && tnum_is_const(tnum_subreg(dst_reg->var_off)))) {
                reg_set_min_max_inv(&other_branch_regs[insn->src_reg], src_reg_in, dst_reg->var_off.value,
                                    tnum_subreg(dst_reg->var_off).value, opcode, is_jmp32);
            } else if (!is_jmp32 && (opcode == BPF_JEQ || opcode == BPF_JNE)) {
                /* Comparing for equality, we can combine knowledge */
                reg_combine_min_max(&other_branch_regs[insn->src_reg], &other_branch_regs[insn->dst_reg], src_reg_in,
                                    dst_reg, opcode);
            }
            if (src_reg_in->id && !WARN_ON_ONCE(src_reg_in->id != other_branch_regs[insn->src_reg].id)) {
                find_equal_scalars(this_branch, src_reg_in);
                find_equal_scalars(other_branch, &other_branch_regs[insn->src_reg]);
            }
        }
    } else if (dst_reg->type == SCALAR_VALUE) {
        reg_set_min_max(&other_branch_regs[insn->dst_reg], dst_reg, insn->imm, (u32)insn->imm, opcode, is_jmp32);
    }

    if (dst_reg->type == SCALAR_VALUE && dst_reg->id &&
        !WARN_ON_ONCE(dst_reg->id != other_branch_regs[insn->dst_reg].id)) {
        find_equal_scalars(this_branch, dst_reg);
        find_equal_scalars(other_branch, &other_branch_regs[insn->dst_reg]);
    }

    /* detect if R == 0 where R is returned from bpf_map_lookup_elem().
     * NOTE: these optimizations below are related with pointer comparison
     *       which will never be JMP32.
     */
    if (!is_jmp32 && BPF_SRC(insn->code) == BPF_K && insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
        type_may_be_null(dst_reg->type)) {
        /* Mark all identical registers in each branch as either
         * safe or unknown depending R == 0 or R != 0 conditional.
         */
        mark_ptr_or_null_regs(this_branch, insn->dst_reg, opcode == BPF_JNE);
        mark_ptr_or_null_regs(other_branch, insn->dst_reg, opcode == BPF_JEQ);
    } else if (!try_match_pkt_pointers(insn, dst_reg, &regs[insn->src_reg], this_branch, other_branch) &&
               is_pointer_value(env, insn->dst_reg)) {
        verbose(env, "R%d pointer comparison prohibited\n", insn->dst_reg);
        return -EACCES;
    }
    if (env->log.level & BPF_LOG_LEVEL) {
        print_verifier_state(env, this_branch->frame[this_branch->curframe]);
    }
    return 0;
}

/* verify BPF_LD_IMM64 instruction */
static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
    struct bpf_insn_aux_data *aux = cur_aux(env);
    struct bpf_reg_state *regs = cur_regs(env);
    struct bpf_reg_state *dst_reg;
    struct bpf_map *map;
    int err;

    if (BPF_SIZE(insn->code) != BPF_DW) {
        verbose(env, "invalid BPF_LD_IMM insn\n");
        return -EINVAL;
    }
    if (insn->off != 0) {
        verbose(env, "BPF_LD_IMM64 uses reserved fields\n");
        return -EINVAL;
    }

    err = check_reg_arg(env, insn->dst_reg, DST_OP);
    if (err) {
        return err;
    }

    dst_reg = &regs[insn->dst_reg];
    if (insn->src_reg == 0) {
        u64 imm = ((u64)(insn + 1)->imm << VERIFIER_THIRTYTWO) | (u32)insn->imm;

        dst_reg->type = SCALAR_VALUE;
        verifier_mark_reg_known(&regs[insn->dst_reg], imm);
        return 0;
    }

    /* All special src_reg cases are listed below. From this point onwards
     * we either succeed and assign a corresponding dst_reg->type after
     * zeroing the offset, or fail and reject the program.
     */
    mark_reg_known_zero(env, regs, insn->dst_reg);

    if (insn->src_reg == BPF_PSEUDO_BTF_ID) {
        dst_reg->type = aux->btf_var.reg_type;
        switch (base_type(dst_reg->type)) {
            case PTR_TO_MEM:
                dst_reg->mem_size = aux->btf_var.mem_size;
                break;
            case PTR_TO_BTF_ID:
            case PTR_TO_PERCPU_BTF_ID:
                dst_reg->btf_id = aux->btf_var.btf_id;
                break;
            default:
                verbose(env, "bpf verifier is misconfigured\n");
                return -EFAULT;
        }
        return 0;
    }

    map = env->used_maps[aux->map_index];
    dst_reg->map_ptr = map;

    if (insn->src_reg == BPF_PSEUDO_MAP_VALUE) {
        dst_reg->type = PTR_TO_MAP_VALUE;
        dst_reg->off = aux->map_off;
        if (map_value_has_spin_lock(map)) {
            dst_reg->id = ++env->id_gen;
        }
    } else if (insn->src_reg == BPF_PSEUDO_MAP_FD) {
        dst_reg->type = CONST_PTR_TO_MAP;
    } else {
        verbose(env, "bpf verifier is misconfigured\n");
        return -EINVAL;
    }

    return 0;
}

static bool may_access_skb(enum bpf_prog_type type)
{
    switch (type) {
        case BPF_PROG_TYPE_SOCKET_FILTER:
        case BPF_PROG_TYPE_SCHED_CLS:
        case BPF_PROG_TYPE_SCHED_ACT:
            return true;
        default:
            return false;
    }
}

/* verify safety of LD_ABS|LD_IND instructions:
 * - they can only appear in the programs where ctx == skb
 * - since they are wrappers of function calls, they scratch R1-R5 registers,
 *   preserve R6-R9, and store return value into R0
 *
 * Implicit input:
 *   ctx == skb == R6 == CTX
 *
 * Explicit input:
 *   SRC == any register
 *   IMM == 32-bit immediate
 *
 * Output:
 *   R0 - 8/16/32-bit skb data converted to cpu endianness
 */
static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
    struct bpf_reg_state *regs = cur_regs(env);
    static const int ctx_reg = BPF_REG_6;
    u8 mode = BPF_MODE(insn->code);
    int i, err;

    if (!may_access_skb(resolve_prog_type(env->prog))) {
        verbose(env, "BPF_LD_[ABS|IND] instructions not allowed for this program type\n");
        return -EINVAL;
    }

    if (!env->ops->gen_ld_abs) {
        verbose(env, "bpf verifier is misconfigured\n");
        return -EINVAL;
    }

    if (insn->dst_reg != BPF_REG_0 || insn->off != 0 || BPF_SIZE(insn->code) == BPF_DW ||
        (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
        verbose(env, "BPF_LD_[ABS|IND] uses reserved fields\n");
        return -EINVAL;
    }

    /* check whether implicit source operand (register R6) is readable */
    err = check_reg_arg(env, ctx_reg, SRC_OP);
    if (err) {
        return err;
    }

    /* Disallow usage of BPF_LD_[ABS|IND] with reference tracking, as
     * gen_ld_abs() may terminate the program at runtime, leading to
     * reference leak.
     */
    err = check_reference_leak(env);
    if (err) {
        verbose(env, "BPF_LD_[ABS|IND] cannot be mixed with socket references\n");
        return err;
    }

    if (env->cur_state->active_spin_lock) {
        verbose(env, "BPF_LD_[ABS|IND] cannot be used inside bpf_spin_lock-ed region\n");
        return -EINVAL;
    }

    if (regs[ctx_reg].type != PTR_TO_CTX) {
        verbose(env, "at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
        return -EINVAL;
    }

    if (mode == BPF_IND) {
        /* check explicit source operand */
        err = check_reg_arg(env, insn->src_reg, SRC_OP);
        if (err) {
            return err;
        }
    }

    err = check_ptr_off_reg(env, &regs[ctx_reg], ctx_reg);
    if (err < 0) {
        return err;
    }

    /* reset caller saved regs to unreadable */
    for (i = 0; i < CALLER_SAVED_REGS; i++) {
        mark_reg_not_init(env, regs, caller_saved[i]);
        check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
    }

    /* mark destination R0 register as readable, since it contains
     * the value fetched from the packet.
     * Already marked as written above.
     */
    mark_reg_unknown(env, regs, BPF_REG_0);
    /* ld_abs load up to 32-bit skb data. */
    regs[BPF_REG_0].subreg_def = env->insn_idx + 1;
    return 0;
}

static int check_return_code(struct bpf_verifier_env *env)
{
    struct tnum enforce_attach_type_range = tnum_unknown;
    const struct bpf_prog *prog = env->prog;
    struct bpf_reg_state *reg;
    struct tnum range = tnum_range(0, 1);
    enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
    int err;
    const bool is_subprog = env->cur_state->frame[0]->subprogno;

    /* LSM and struct_ops func-ptr's return type could be "void" */
    if (!is_subprog && (prog_type == BPF_PROG_TYPE_STRUCT_OPS || prog_type == BPF_PROG_TYPE_LSM) &&
        !prog->aux->attach_func_proto->type) {
        return 0;
    }

    /* eBPF calling convetion is such that R0 is used
     * to return the value from eBPF program.
     * Make sure that it's readable at this time
     * of bpf_exit, which means that program wrote
     * something into it earlier
     */
    err = check_reg_arg(env, BPF_REG_0, SRC_OP);
    if (err) {
        return err;
    }

    if (is_pointer_value(env, BPF_REG_0)) {
        verbose(env, "R0 leaks addr as return value\n");
        return -EACCES;
    }

    reg = cur_regs(env) + BPF_REG_0;
    if (is_subprog) {
        if (reg->type != SCALAR_VALUE) {
            verbose(env, "At subprogram exit the register R0 is not a scalar value (%s)\n",
                    reg_type_str(env, reg->type));
            return -EINVAL;
        }
        return 0;
    }

    switch (prog_type) {
        case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
            if (env->prog->expected_attach_type == BPF_CGROUP_UDP4_RECVMSG ||
                env->prog->expected_attach_type == BPF_CGROUP_UDP6_RECVMSG ||
                env->prog->expected_attach_type == BPF_CGROUP_INET4_GETPEERNAME ||
                env->prog->expected_attach_type == BPF_CGROUP_INET6_GETPEERNAME ||
                env->prog->expected_attach_type == BPF_CGROUP_INET4_GETSOCKNAME ||
                env->prog->expected_attach_type == BPF_CGROUP_INET6_GETSOCKNAME) {
                range = tnum_range(1, 1);
            }
            break;
        case BPF_PROG_TYPE_CGROUP_SKB:
            if (env->prog->expected_attach_type == BPF_CGROUP_INET_EGRESS) {
                range = tnum_range(0, 3);
                enforce_attach_type_range = tnum_range(2, 3);
            }
            break;
        case BPF_PROG_TYPE_CGROUP_SOCK:
        case BPF_PROG_TYPE_SOCK_OPS:
        case BPF_PROG_TYPE_CGROUP_DEVICE:
        case BPF_PROG_TYPE_CGROUP_SYSCTL:
        case BPF_PROG_TYPE_CGROUP_SOCKOPT:
            break;
        case BPF_PROG_TYPE_RAW_TRACEPOINT:
            if (!env->prog->aux->attach_btf_id) {
                return 0;
            }
            range = tnum_const(0);
            break;
        case BPF_PROG_TYPE_TRACING:
            switch (env->prog->expected_attach_type) {
                case BPF_TRACE_FENTRY:
                case BPF_TRACE_FEXIT:
                    range = tnum_const(0);
                    break;
                case BPF_TRACE_RAW_TP:
                case BPF_MODIFY_RETURN:
                    return 0;
                case BPF_TRACE_ITER:
                    break;
                default:
                    return -ENOTSUPP;
            }
            break;
        case BPF_PROG_TYPE_SK_LOOKUP:
            range = tnum_range(SK_DROP, SK_PASS);
            break;
        case BPF_PROG_TYPE_EXT:
            /* freplace program can return anything as its return value
             * depends on the to-be-replaced kernel func or bpf program.
             */
        default:
            return 0;
    }

    if (reg->type != SCALAR_VALUE) {
        verbose(env, "At program exit the register R0 is not a known value (%s)\n", reg_type_str(env, reg->type));
        return -EINVAL;
    }

    if (!tnum_in(range, reg->var_off)) {
        char tn_buf[48];

        verbose(env, "At program exit the register R0 ");
        if (!tnum_is_unknown(reg->var_off)) {
            tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
            verbose(env, "has value %s", tn_buf);
        } else {
            verbose(env, "has unknown scalar value");
        }
        tnum_strn(tn_buf, sizeof(tn_buf), range);
        verbose(env, " should have been in %s\n", tn_buf);
        return -EINVAL;
    }

    if (!tnum_is_unknown(enforce_attach_type_range) && tnum_in(enforce_attach_type_range, reg->var_off)) {
        env->prog->enforce_expected_attach_type = 1;
    }
    return 0;
}

/* non-recursive DFS pseudo code
 * 1  procedure DFS-iterative(G,v):
 * 2      label v as discovered
 * 3      let S be a stack
 * 4      S.push(v)
 * 5      while S is not empty
 * 6            t <- S.pop()
 * 7            if t is what we're looking for:
 * 8                return t
 * 9            for all edges e in G.adjacentEdges(t) do
 * 10               if edge e is already labelled
 * 11                   continue with the next edge
 * 12               w <- G.adjacentVertex(t,e)
 * 13               if vertex w is not discovered and not explored
 * 14                   label e as tree-edge
 * 15                   label w as discovered
 * 16                   S.push(w)
 * 17                   continue at 5
 * 18               else if vertex w is discovered
 * 19                   label e as back-edge
 * 20               else
 * 21                   // vertex w is explored
 * 22                   label e as forward- or cross-edge
 * 23           label t as explored
 * 24           S.pop()
 *
 * convention:
 * 0x10 - discovered
 * 0x11 - discovered and fall-through edge labelled
 * 0x12 - discovered and fall-through and branch edges labelled
 * 0x20 - explored
 */

enum {
    DISCOVERED = 0x10,
    EXPLORED = 0x20,
    FALLTHROUGH = 1,
    BRANCH = 2,
};

static u32 state_htab_size(struct bpf_verifier_env *env)
{
    return env->prog->len;
}

static struct bpf_verifier_state_list **explored_state(struct bpf_verifier_env *env, int idx)
{
    struct bpf_verifier_state *cur = env->cur_state;
    struct bpf_func_state *state = cur->frame[cur->curframe];

    return &env->explored_states[(idx ^ state->callsite) % state_htab_size(env)];
}

static void init_explored_state(struct bpf_verifier_env *env, int idx)
{
    env->insn_aux_data[idx].prune_point = true;
}

/* t, w, e - match pseudo-code above:
 * t - index of current instruction
 * w - next instruction
 * e - edge
 */
static int push_insn(int t, int w, int e, struct bpf_verifier_env *env, bool loop_ok)
{
    int *insn_stack = env->cfg.insn_stack;
    int *insn_state = env->cfg.insn_state;

    if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH)) {
        return 0;
    }

    if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH)) {
        return 0;
    }

    if (w < 0 || w >= env->prog->len) {
        verbose_linfo(env, t, "%d: ", t);
        verbose(env, "jump out of range from insn %d to %d\n", t, w);
        return -EINVAL;
    }

    if (e == BRANCH) {
        /* mark branch target for state pruning */
        init_explored_state(env, w);
    }

    if (insn_state[w] == 0) {
        /* tree-edge */
        insn_state[t] = DISCOVERED | e;
        insn_state[w] = DISCOVERED;
        if (env->cfg.cur_stack >= env->prog->len) {
            return -E2BIG;
        }
        insn_stack[env->cfg.cur_stack++] = w;
        return 1;
    } else if ((insn_state[w] & 0xF0) == DISCOVERED) {
        if (loop_ok && env->bpf_capable) {
            return 0;
        }
        verbose_linfo(env, t, "%d: ", t);
        verbose_linfo(env, w, "%d: ", w);
        verbose(env, "back-edge from insn %d to %d\n", t, w);
        return -EINVAL;
    } else if (insn_state[w] == EXPLORED) {
        /* forward- or cross-edge */
        insn_state[t] = DISCOVERED | e;
    } else {
        verbose(env, "insn state internal bug\n");
        return -EFAULT;
    }
    return 0;
}

/* non-recursive depth-first-search to detect loops in BPF program
 * loop == back-edge in directed graph
 */
static int check_cfg(struct bpf_verifier_env *env)
{
    struct bpf_insn *insns = env->prog->insnsi;
    int insn_cnt = env->prog->len;
    int *insn_stack, *insn_state;
    int ret = 0;
    int i, t;

    insn_state = env->cfg.insn_state = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
    if (!insn_state) {
        return -ENOMEM;
    }

    insn_stack = env->cfg.insn_stack = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
    if (!insn_stack) {
        kvfree(insn_state);
        return -ENOMEM;
    }

    insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */
    insn_stack[0] = 0;          /* 0 is the first instruction */
    env->cfg.cur_stack = 1;

    while (1) {
        if (env->cfg.cur_stack == 0) {
            goto check_state;
        }
        t = insn_stack[env->cfg.cur_stack - 1];

        if (BPF_CLASS(insns[t].code) == BPF_JMP || BPF_CLASS(insns[t].code) == BPF_JMP32) {
            u8 opcode = BPF_OP(insns[t].code);
            if (opcode == BPF_EXIT) {
                goto mark_explored;
            } else if (opcode == BPF_CALL) {
                ret = push_insn(t, t + 1, FALLTHROUGH, env, false);
                if (ret == 1) {
                    continue;
                } else if (ret < 0) {
                    goto err_free;
                }
                if (t + 1 < insn_cnt) {
                    init_explored_state(env, t + 1);
                }
                if (insns[t].src_reg == BPF_PSEUDO_CALL) {
                    init_explored_state(env, t);
                    ret = push_insn(t, t + insns[t].imm + 1, BRANCH, env, false);
                    if (ret == 1) {
                        continue;
                    } else if (ret < 0) {
                        goto err_free;
                    }
                }
            } else if (opcode == BPF_JA) {
                if (BPF_SRC(insns[t].code) != BPF_K) {
                    ret = -EINVAL;
                    goto err_free;
                }
                /* unconditional jump with single edge */
                ret = push_insn(t, t + insns[t].off + 1, FALLTHROUGH, env, true);
                if (ret == 1) {
                    continue;
                } else if (ret < 0) {
                    goto err_free;
                }
                /* unconditional jmp is not a good pruning point,
                 * but it's marked, since backtracking needs
                 * to record jmp history in is_state_visited().
                 */
                init_explored_state(env, t + insns[t].off + 1);
                /* tell verifier to check for equivalent states
                 * after every call and jump
                 */
                if (t + 1 < insn_cnt) {
                    init_explored_state(env, t + 1);
                }
            } else {
                /* conditional jump with two edges */
                init_explored_state(env, t);
                ret = push_insn(t, t + 1, FALLTHROUGH, env, true);
                if (ret == 1) {
                    continue;
                } else if (ret < 0) {
                    goto err_free;
                }

                ret = push_insn(t, t + insns[t].off + 1, BRANCH, env, true);
                if (ret == 1) {
                    continue;
                } else if (ret < 0) {
                    goto err_free;
                }
            }
        } else {
            /* all other non-branch instructions with single
             * fall-through edge
             */
            ret = push_insn(t, t + 1, FALLTHROUGH, env, false);
            if (ret == 1) {
                continue;
            } else if (ret < 0) {
                goto err_free;
            }
        }

    mark_explored:
        insn_state[t] = EXPLORED;
        if (env->cfg.cur_stack-- <= 0) {
            verbose(env, "pop stack internal bug\n");
            ret = -EFAULT;
            goto err_free;
        }
        continue;
    }

check_state:
    for (i = 0; i < insn_cnt; i++) {
        if (insn_state[i] != EXPLORED) {
            verbose(env, "unreachable insn %d\n", i);
            ret = -EINVAL;
            goto err_free;
        }
    }
    ret = 0; /* cfg looks good */

err_free:
    kvfree(insn_state);
    kvfree(insn_stack);
    env->cfg.insn_state = env->cfg.insn_stack = NULL;
    return ret;
}

static int check_abnormal_return(struct bpf_verifier_env *env)
{
    int i;

    for (i = 1; i < env->subprog_cnt; i++) {
        if (env->subprog_info[i].has_ld_abs) {
            verbose(env, "LD_ABS is not allowed in subprogs without BTF\n");
            return -EINVAL;
        }
        if (env->subprog_info[i].has_tail_call) {
            verbose(env, "tail_call is not allowed in subprogs without BTF\n");
            return -EINVAL;
        }
    }
    return 0;
}

/* The minimum supported BTF func info size */
#define MIN_BPF_FUNCINFO_SIZE 8
#define MAX_FUNCINFO_REC_SIZE 252

static int check_btf_func(struct bpf_verifier_env *env, const union bpf_attr *attr, union bpf_attr __user *uattr)
{
    const struct btf_type *type, *func_proto, *ret_type;
    u32 i, nfuncs, urec_size, min_size;
    u32 krec_size = sizeof(struct bpf_func_info);
    struct bpf_func_info *krecord;
    struct bpf_func_info_aux *info_aux = NULL;
    struct bpf_prog *prog;
    const struct btf *btf;
    void __user *urecord;
    u32 prev_offset = 0;
    bool scalar_return;
    int ret = -ENOMEM;

    nfuncs = attr->func_info_cnt;
    if (!nfuncs) {
        if (check_abnormal_return(env)) {
            return -EINVAL;
        }
        return 0;
    }

    if (nfuncs != env->subprog_cnt) {
        verbose(env, "number of funcs in func_info doesn't match number of subprogs\n");
        return -EINVAL;
    }

    urec_size = attr->func_info_rec_size;
    if (urec_size < MIN_BPF_FUNCINFO_SIZE || urec_size > MAX_FUNCINFO_REC_SIZE || urec_size % sizeof(u32)) {
        verbose(env, "invalid func info rec size %u\n", urec_size);
        return -EINVAL;
    }

    prog = env->prog;
    btf = prog->aux->btf;

    urecord = u64_to_user_ptr(attr->func_info);
    min_size = min_t(u32, krec_size, urec_size);

    krecord = kvcalloc(nfuncs, krec_size, GFP_KERNEL | __GFP_NOWARN);
    if (!krecord) {
        return -ENOMEM;
    }
    info_aux = kcalloc(nfuncs, sizeof(*info_aux), GFP_KERNEL | __GFP_NOWARN);
    if (!info_aux) {
        goto err_free;
    }

    for (i = 0; i < nfuncs; i++) {
        ret = bpf_check_uarg_tail_zero(urecord, krec_size, urec_size);
        if (ret) {
            if (ret == -E2BIG) {
                verbose(env, "nonzero tailing record in func info");
                /* set the size kernel expects so loader can zero
                 * out the rest of the record.
                 */
                if (put_user(min_size, &uattr->func_info_rec_size)) {
                    ret = -EFAULT;
                }
            }
            goto err_free;
        }

        if (copy_from_user(&krecord[i], urecord, min_size)) {
            ret = -EFAULT;
            goto err_free;
        }

        /* check insn_off */
        ret = -EINVAL;
        if (i == 0) {
            if (krecord[i].insn_off) {
                verbose(env, "nonzero insn_off %u for the first func info record", krecord[i].insn_off);
                goto err_free;
            }
        } else if (krecord[i].insn_off <= prev_offset) {
            verbose(env, "same or smaller insn offset (%u) than previous func info record (%u)", krecord[i].insn_off,
                    prev_offset);
            goto err_free;
        }

        if (env->subprog_info[i].start != krecord[i].insn_off) {
            verbose(env, "func_info BTF section doesn't match subprog layout in BPF program\n");
            goto err_free;
        }

        /* check type_id */
        type = btf_type_by_id(btf, krecord[i].type_id);
        if (!type || !btf_type_is_func(type)) {
            verbose(env, "invalid type id %d in func info", krecord[i].type_id);
            goto err_free;
        }
        info_aux[i].linkage = BTF_INFO_VLEN(type->info);

        func_proto = btf_type_by_id(btf, type->type);
        if (unlikely(!func_proto || !btf_type_is_func_proto(func_proto))) {
            /* btf_func_check() already verified it during BTF load */
            goto err_free;
        }
        ret_type = btf_type_skip_modifiers(btf, func_proto->type, NULL);
        scalar_return = btf_type_is_small_int(ret_type) || btf_type_is_enum(ret_type);
        if (i && !scalar_return && env->subprog_info[i].has_ld_abs) {
            verbose(env, "LD_ABS is only allowed in functions that return 'int'.\n");
            goto err_free;
        }
        if (i && !scalar_return && env->subprog_info[i].has_tail_call) {
            verbose(env, "tail_call is only allowed in functions that return 'int'.\n");
            goto err_free;
        }

        prev_offset = krecord[i].insn_off;
        urecord += urec_size;
    }

    prog->aux->func_info = krecord;
    prog->aux->func_info_cnt = nfuncs;
    prog->aux->func_info_aux = info_aux;
    return 0;

err_free:
    kvfree(krecord);
    kfree(info_aux);
    return ret;
}

static void adjust_btf_func(struct bpf_verifier_env *env)
{
    struct bpf_prog_aux *aux = env->prog->aux;
    int i;

    if (!aux->func_info) {
        return;
    }

    for (i = 0; i < env->subprog_cnt; i++) {
        aux->func_info[i].insn_off = env->subprog_info[i].start;
    }
}

#define MIN_BPF_LINEINFO_SIZE                                                                                          \
    (offsetof(struct bpf_line_info, line_col) + sizeof(((struct bpf_line_info *)(0))->line_col))
#define MAX_LINEINFO_REC_SIZE MAX_FUNCINFO_REC_SIZE

static int check_btf_line(struct bpf_verifier_env *env, const union bpf_attr *attr, union bpf_attr __user *uattr)
{
    u32 i, s, nr_linfo, ncopy, expected_size, rec_size, prev_offset = 0;
    struct bpf_subprog_info *sub;
    struct bpf_line_info *linfo;
    struct bpf_prog *prog;
    const struct btf *btf;
    void __user *ulinfo;
    int err;

    nr_linfo = attr->line_info_cnt;
    if (!nr_linfo) {
        return 0;
    }
    if (nr_linfo > INT_MAX / sizeof(struct bpf_line_info)) {
        return -EINVAL;
    }

    rec_size = attr->line_info_rec_size;
    if (rec_size < MIN_BPF_LINEINFO_SIZE || rec_size > MAX_LINEINFO_REC_SIZE || rec_size & (sizeof(u32) - 1)) {
        return -EINVAL;
    }

    /* Need to zero it in case the userspace may
     * pass in a smaller bpf_line_info object.
     */
    linfo = kvcalloc(nr_linfo, sizeof(struct bpf_line_info), GFP_KERNEL | __GFP_NOWARN);
    if (!linfo) {
        return -ENOMEM;
    }

    prog = env->prog;
    btf = prog->aux->btf;

    s = 0;
    sub = env->subprog_info;
    ulinfo = u64_to_user_ptr(attr->line_info);
    expected_size = sizeof(struct bpf_line_info);
    ncopy = min_t(u32, expected_size, rec_size);
    for (i = 0; i < nr_linfo; i++) {
        err = bpf_check_uarg_tail_zero(ulinfo, expected_size, rec_size);
        if (err) {
            if (err == -E2BIG) {
                verbose(env, "nonzero tailing record in line_info");
                if (put_user(expected_size, &uattr->line_info_rec_size)) {
                    err = -EFAULT;
                }
            }
            goto err_free;
        }

        if (copy_from_user(&linfo[i], ulinfo, ncopy)) {
            err = -EFAULT;
            goto err_free;
        }

        /*
         * Check insn_off to ensure
         * 1) strictly increasing AND
         * 2) bounded by prog->len
         *
         * The linfo[0].insn_off == 0 check logically falls into
         * the later "missing bpf_line_info for func..." case
         * because the first linfo[0].insn_off must be the
         * first sub also and the first sub must have
         * subprog_info[0].start == 0.
         */
        if ((i && linfo[i].insn_off <= prev_offset) || linfo[i].insn_off >= prog->len) {
            verbose(env, "Invalid line_info[%u].insn_off:%u (prev_offset:%u prog->len:%u)\n", i, linfo[i].insn_off,
                    prev_offset, prog->len);
            err = -EINVAL;
            goto err_free;
        }

        if (!prog->insnsi[linfo[i].insn_off].code) {
            verbose(env, "Invalid insn code at line_info[%u].insn_off\n", i);
            err = -EINVAL;
            goto err_free;
        }

        if (!btf_name_by_offset(btf, linfo[i].line_off) || !btf_name_by_offset(btf, linfo[i].file_name_off)) {
            verbose(env, "Invalid line_info[%u].line_off or .file_name_off\n", i);
            err = -EINVAL;
            goto err_free;
        }

        if (s != env->subprog_cnt) {
            if (linfo[i].insn_off == sub[s].start) {
                sub[s].linfo_idx = i;
                s++;
            } else if (sub[s].start < linfo[i].insn_off) {
                verbose(env, "missing bpf_line_info for func#%u\n", s);
                err = -EINVAL;
                goto err_free;
            }
        }

        prev_offset = linfo[i].insn_off;
        ulinfo += rec_size;
    }

    if (s != env->subprog_cnt) {
        verbose(env, "missing bpf_line_info for %u funcs starting from func#%u\n", env->subprog_cnt - s, s);
        err = -EINVAL;
        goto err_free;
    }

    prog->aux->linfo = linfo;
    prog->aux->nr_linfo = nr_linfo;

    return 0;

err_free:
    kvfree(linfo);
    return err;
}

static int check_btf_info(struct bpf_verifier_env *env, const union bpf_attr *attr, union bpf_attr __user *uattr)
{
    struct btf *btf;
    int err;

    if (!attr->func_info_cnt && !attr->line_info_cnt) {
        if (check_abnormal_return(env)) {
            return -EINVAL;
        }
        return 0;
    }

    btf = btf_get_by_fd(attr->prog_btf_fd);
    if (IS_ERR(btf)) {
        return PTR_ERR(btf);
    }
    env->prog->aux->btf = btf;

    err = check_btf_func(env, attr, uattr);
    if (err) {
        return err;
    }

    err = check_btf_line(env, attr, uattr);
    if (err) {
        return err;
    }

    return 0;
}

/* check %cur's range satisfies %old's */
static bool range_within(struct bpf_reg_state *old, struct bpf_reg_state *cur)
{
    return old->umin_value <= cur->umin_value && old->umax_value >= cur->umax_value &&
           old->smin_value <= cur->smin_value && old->smax_value >= cur->smax_value &&
           old->u32_min_value <= cur->u32_min_value && old->u32_max_value >= cur->u32_max_value &&
           old->s32_min_value <= cur->s32_min_value && old->s32_max_value >= cur->s32_max_value;
}

/* If in the old state two registers had the same id, then they need to have
 * the same id in the new state as well.  But that id could be different from
 * the old state, so we need to track the mapping from old to new ids.
 * Once we have seen that, say, a reg with old id 5 had new id 9, any subsequent
 * regs with old id 5 must also have new id 9 for the new state to be safe.  But
 * regs with a different old id could still have new id 9, we don't care about
 * that.
 * So we look through our idmap to see if this old id has been seen before.  If
 * so, we require the new id to match; otherwise, we add the id pair to the map.
 */
static bool check_ids(u32 old_id, u32 cur_id, struct bpf_id_pair *idmap)
{
    unsigned int i;

    for (i = 0; i < BPF_ID_MAP_SIZE; i++) {
        if (!idmap[i].old) {
            /* Reached an empty slot; haven't seen this id before */
            idmap[i].old = old_id;
            idmap[i].cur = cur_id;
            return true;
        }
        if (idmap[i].old == old_id) {
            return idmap[i].cur == cur_id;
        }
    }
    /* We ran out of idmap slots, which should be impossible */
    WARN_ON_ONCE(1);
    return false;
}

static void clean_func_state(struct bpf_verifier_env *env, struct bpf_func_state *st)
{
    enum bpf_reg_liveness live;
    int i, j;

    for (i = 0; i < BPF_REG_FP; i++) {
        live = st->regs[i].live;
        /* liveness must not touch this register anymore */
        st->regs[i].live |= REG_LIVE_DONE;
        if (!(live & REG_LIVE_READ)) {
            /* since the register is unused, clear its state
             * to make further comparison simpler
             */
            verifier_mark_reg_not_init(env, &st->regs[i]);
        }
    }

    for (i = 0; i < st->allocated_stack / BPF_REG_SIZE; i++) {
        live = st->stack[i].spilled_ptr.live;
        /* liveness must not touch this stack slot anymore */
        st->stack[i].spilled_ptr.live |= REG_LIVE_DONE;
        if (!(live & REG_LIVE_READ)) {
            verifier_mark_reg_not_init(env, &st->stack[i].spilled_ptr);
            for (j = 0; j < BPF_REG_SIZE; j++) {
                st->stack[i].slot_type[j] = STACK_INVALID;
            }
        }
    }
}

static void clean_verifier_state(struct bpf_verifier_env *env, struct bpf_verifier_state *st)
{
    int i;

    if (st->frame[0]->regs[0].live & REG_LIVE_DONE) {
        /* all regs in this state in all frames were already marked */
        return;
    }

    for (i = 0; i <= st->curframe; i++) {
        clean_func_state(env, st->frame[i]);
    }
}

/* the parentage chains form a tree.
 * the verifier states are added to state lists at given insn and
 * pushed into state stack for future exploration.
 * when the verifier reaches bpf_exit insn some of the verifer states
 * stored in the state lists have their final liveness state already,
 * but a lot of states will get revised from liveness point of view when
 * the verifier explores other branches.
 * 1: r0 = 1
 * 2: if r1 == 100 goto pc+1
 * 3: r0 = 2
 * 4: exit
 * when the verifier reaches exit insn the register r0 in the state list of
 * insn 2 will be seen as !REG_LIVE_READ. Then the verifier pops the other_branch
 * of insn 2 and goes exploring further. At the insn 4 it will walk the
 * parentage chain from insn 4 into insn 2 and will mark r0 as REG_LIVE_READ.
 *
 * Since the verifier pushes the branch states as it sees them while exploring
 * the program the condition of walking the branch instruction for the second
 * time means that all states below this branch were already explored and
 * their final liveness markes are already propagated.
 * Hence when the verifier completes the search of state list in is_state_visited()
 * we can call this clean_live_states() function to mark all liveness states
 * as REG_LIVE_DONE to indicate that 'parent' pointers of 'struct bpf_reg_state'
 * will not be used.
 * This function also clears the registers and stack for states that !READ
 * to simplify state merging.
 *
 * Important note here that walking the same branch instruction in the callee
 * doesn't meant that the states are DONE. The verifier has to compare
 * the callsites
 */
static void clean_live_states(struct bpf_verifier_env *env, int insn, struct bpf_verifier_state *cur)
{
    struct bpf_verifier_state_list *sl;
    int i;

    sl = *explored_state(env, insn);
    while (sl) {
        if (sl->state.branches) {
            goto next;
        }
        if (sl->state.insn_idx != insn || sl->state.curframe != cur->curframe) {
            goto next;
        }
        for (i = 0; i <= cur->curframe; i++) {
            if (sl->state.frame[i]->callsite != cur->frame[i]->callsite) {
                goto next;
            }
        }
        clean_verifier_state(env, &sl->state);
    next:
        sl = sl->next;
    }
}

/* Returns true if (rold safe implies rcur safe) */
static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold, struct bpf_reg_state *rcur,
                    struct bpf_id_pair *idmap)
{
    bool equal;

    if (!(rold->live & REG_LIVE_READ)) {
        /* explored state didn't use this */
        return true;
    }

    equal = memcmp(rold, rcur, offsetof(struct bpf_reg_state, parent)) == 0;

    if (rold->type == PTR_TO_STACK) {
        /* two stack pointers are equal only if they're pointing to
         * the same stack frame, since fp-8 in foo != fp-8 in bar
         */
        return equal && rold->frameno == rcur->frameno;
    }

    if (equal) {
        return true;
    }

    if (rold->type == NOT_INIT) {
        /* explored state can't have used this */
        return true;
    }
    if (rcur->type == NOT_INIT) {
        return false;
    }
    switch (base_type(rold->type)) {
        case SCALAR_VALUE:
            if (env->explore_alu_limits) {
                return false;
            }
            if (rcur->type == SCALAR_VALUE) {
                if (!rold->precise && !rcur->precise) {
                    return true;
                }
                /* new val must satisfy old val knowledge */
                return range_within(rold, rcur) && tnum_in(rold->var_off, rcur->var_off);
            } else {
                /* We're trying to use a pointer in place of a scalar.
                 * Even if the scalar was unbounded, this could lead to
                 * pointer leaks because scalars are allowed to leak
                 * while pointers are not. We could make this safe in
                 * special cases if root is calling us, but it's
                 * probably not worth the hassle.
                 */
                return false;
            }
        case PTR_TO_MAP_VALUE:
            /* a PTR_TO_MAP_VALUE could be safe to use as a
             * PTR_TO_MAP_VALUE_OR_NULL into the same map.
             * However, if the old PTR_TO_MAP_VALUE_OR_NULL then got NULL-
             * checked, doing so could have affected others with the same
             * id, and we can't check for that because we lost the id when
             * we converted to a PTR_TO_MAP_VALUE.
             */
            if (type_may_be_null(rold->type)) {
                if (!type_may_be_null(rcur->type)) {
                    return false;
                }
                if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, id))) {
                    return false;
                }
                /* Check our ids match any regs they're supposed to */
                return check_ids(rold->id, rcur->id, idmap);
            }

            /* If the new min/max/var_off satisfy the old ones and
             * everything else matches, we are OK.
             * 'id' is not compared, since it's only used for maps with
             * bpf_spin_lock inside map element and in such cases if
             * the rest of the prog is valid for one map element then
             * it's valid for all map elements regardless of the key
             * used in bpf_map_lookup()
             */
            return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 && range_within(rold, rcur) &&
                   tnum_in(rold->var_off, rcur->var_off);
        case PTR_TO_PACKET_META:
        case PTR_TO_PACKET:
            if (rcur->type != rold->type) {
                return false;
            }
            /* We must have at least as much range as the old ptr
             * did, so that any accesses which were safe before are
             * still safe.  This is true even if old range < old off,
             * since someone could have accessed through (ptr - k), or
             * even done ptr -= k in a register, to get a safe access.
             */
            if (rold->range > rcur->range) {
                return false;
            }
            /* If the offsets don't match, we can't trust our alignment;
             * nor can we be sure that we won't fall out of range.
             */
            if (rold->off != rcur->off) {
                return false;
            }
            /* id relations must be preserved */
            if (rold->id && !check_ids(rold->id, rcur->id, idmap)) {
                return false;
            }
            /* new val must satisfy old val knowledge */
            return range_within(rold, rcur) && tnum_in(rold->var_off, rcur->var_off);
        case PTR_TO_CTX:
        case CONST_PTR_TO_MAP:
        case PTR_TO_PACKET_END:
        case PTR_TO_FLOW_KEYS:
        case PTR_TO_SOCKET:
        case PTR_TO_SOCK_COMMON:
        case PTR_TO_TCP_SOCK:
        case PTR_TO_XDP_SOCK:
            /* Only valid matches are exact, which memcmp() above
             * would have accepted
             */
        default:
            /* Don't know what's going on, just say it's not safe */
            return false;
    }

    /* Shouldn't get here; if we do, say it's not safe */
    WARN_ON_ONCE(1);
    return false;
}

static bool stacksafe(struct bpf_verifier_env *env, struct bpf_func_state *old, struct bpf_func_state *cur,
                      struct bpf_id_pair *idmap)
{
    int i, spi;

    /* walk slots of the explored stack and ignore any additional
     * slots in the current stack, since explored(safe) state
     * didn't use them
     */
    for (i = 0; i < old->allocated_stack; i++) {
        spi = i / BPF_REG_SIZE;

        if (!(old->stack[spi].spilled_ptr.live & REG_LIVE_READ)) {
            i += BPF_REG_SIZE - 1;
            /* explored state didn't use this */
            continue;
        }

        if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_INVALID) {
            continue;
        }

        /* explored stack has more populated slots than current stack
         * and these slots were used
         */
        if (i >= cur->allocated_stack) {
            return false;
        }

        /* if old state was safe with misc data in the stack
         * it will be safe with zero-initialized stack.
         * The opposite is not true
         */
        if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_MISC &&
            cur->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_ZERO) {
            continue;
        }
        if (old->stack[spi].slot_type[i % BPF_REG_SIZE] != cur->stack[spi].slot_type[i % BPF_REG_SIZE]) {
            /* Ex: old explored (safe) state has STACK_SPILL in
             * this stack slot, but current has STACK_MISC ->
             * this verifier states are not equivalent,
             * return false to continue verification of this path
             */
            return false;
        }
        if (i % BPF_REG_SIZE) {
            continue;
        }
        if (old->stack[spi].slot_type[0] != STACK_SPILL) {
            continue;
        }
        if (!regsafe(env, &old->stack[spi].spilled_ptr, &cur->stack[spi].spilled_ptr, idmap)) {
            /* when explored and current stack slot are both storing
             * spilled registers, check that stored pointers types
             * are the same as well.
             * Ex: explored safe path could have stored
             * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -8}
             * but current path has stored:
             * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -16}
             * such verifier states are not equivalent.
             * return false to continue verification of this path
             */
            return false;
        }
    }
    return true;
}

static bool refsafe(struct bpf_func_state *old, struct bpf_func_state *cur)
{
    if (old->acquired_refs != cur->acquired_refs) {
        return false;
    }
    return !memcmp(old->refs, cur->refs, sizeof(*old->refs) * old->acquired_refs);
}

/* compare two verifier states
 *
 * all states stored in state_list are known to be valid, since
 * verifier reached 'bpf_exit' instruction through them
 *
 * this function is called when verifier exploring different branches of
 * execution popped from the state stack. If it sees an old state that has
 * more strict register state and more strict stack state then this execution
 * branch doesn't need to be explored further, since verifier already
 * concluded that more strict state leads to valid finish.
 *
 * Therefore two states are equivalent if register state is more conservative
 * and explored stack state is more conservative than the current one.
 * Example:
 *       explored                   current
 * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
 * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
 *
 * In other words if current stack state (one being explored) has more
 * valid slots than old one that already passed validation, it means
 * the verifier can stop exploring and conclude that current state is valid too
 *
 * Similarly with registers. If explored state has register type as invalid
 * whereas register type in current state is meaningful, it means that
 * the current state will reach 'bpf_exit' instruction safely
 */
static bool func_states_equal(struct bpf_verifier_env *env, struct bpf_func_state *old, struct bpf_func_state *cur)
{
    int i;

    memset(env->idmap_scratch, 0, sizeof(env->idmap_scratch));
    for (i = 0; i < MAX_BPF_REG; i++) {
        if (!regsafe(env, &old->regs[i], &cur->regs[i], env->idmap_scratch)) {
            return false;
        }
    }

    if (!stacksafe(env, old, cur, env->idmap_scratch)) {
        return false;
    }

    if (!refsafe(old, cur)) {
        return false;
    }

    return true;
}

static bool states_equal(struct bpf_verifier_env *env, struct bpf_verifier_state *old, struct bpf_verifier_state *cur)
{
    int i;

    if (old->curframe != cur->curframe) {
        return false;
    }

    /* Verification state from speculative execution simulation
     * must never prune a non-speculative execution one.
     */
    if (old->speculative && !cur->speculative) {
        return false;
    }

    if (old->active_spin_lock != cur->active_spin_lock) {
        return false;
    }

    /* for states to be equal callsites have to be the same
     * and all frame states need to be equivalent
     */
    for (i = 0; i <= old->curframe; i++) {
        if (old->frame[i]->callsite != cur->frame[i]->callsite) {
            return false;
        }
        if (!func_states_equal(env, old->frame[i], cur->frame[i])) {
            return false;
        }
    }
    return true;
}

/* Return 0 if no propagation happened. Return negative error code if error
 * happened. Otherwise, return the propagated bit.
 */
static int propagate_liveness_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
                                  struct bpf_reg_state *parent_reg)
{
    u8 parent_flag = parent_reg->live & REG_LIVE_READ;
    u8 flag = reg->live & REG_LIVE_READ;
    int err;

    /* When comes here, read flags of PARENT_REG or REG could be any of
     * REG_LIVE_READ64, REG_LIVE_READ32, REG_LIVE_NONE. There is no need
     * of propagation if PARENT_REG has strongest REG_LIVE_READ64.
     */
    if (parent_flag == REG_LIVE_READ64 ||
        /* Or if there is no read flag from REG. */
        !flag ||
        /* Or if the read flag from REG is the same as PARENT_REG. */
        parent_flag == flag) {
        return 0;
    }

    err = mark_reg_read(env, reg, parent_reg, flag);
    if (err) {
        return err;
    }

    return flag;
}

/* A write screens off any subsequent reads; but write marks come from the
 * straight-line code between a state and its parent.  When we arrive at an
 * equivalent state (jump target or such) we didn't arrive by the straight-line
 * code, so read marks in the state must propagate to the parent regardless
 * of the state's write marks. That's what 'parent == state->parent' comparison
 * in mark_reg_read() is for.
 */
static int propagate_liveness(struct bpf_verifier_env *env, const struct bpf_verifier_state *vstate,
                              struct bpf_verifier_state *vparent)
{
    struct bpf_reg_state *state_reg, *parent_reg;
    struct bpf_func_state *state, *parent;
    int i, frame, err = 0;

    if (vparent->curframe != vstate->curframe) {
        WARN(1, "propagate_live: parent frame %d current frame %d\n", vparent->curframe, vstate->curframe);
        return -EFAULT;
    }
    /* Propagate read liveness of registers... */
    BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG);
    for (frame = 0; frame <= vstate->curframe; frame++) {
        parent = vparent->frame[frame];
        state = vstate->frame[frame];
        parent_reg = parent->regs;
        state_reg = state->regs;
        /* We don't need to worry about FP liveness, it's read-only */
        for (i = frame < vstate->curframe ? BPF_REG_6 : 0; i < BPF_REG_FP; i++) {
            err = propagate_liveness_reg(env, &state_reg[i], &parent_reg[i]);
            if (err < 0) {
                return err;
            }
            if (err == REG_LIVE_READ64) {
                mark_insn_zext(env, &parent_reg[i]);
            }
        }

        /* Propagate stack slots. */
        for (i = 0; i < state->allocated_stack / BPF_REG_SIZE && i < parent->allocated_stack / BPF_REG_SIZE; i++) {
            parent_reg = &parent->stack[i].spilled_ptr;
            state_reg = &state->stack[i].spilled_ptr;
            err = propagate_liveness_reg(env, state_reg, parent_reg);
            if (err < 0) {
                return err;
            }
        }
    }
    return 0;
}

/* find precise scalars in the previous equivalent state and
 * propagate them into the current state
 */
static int propagate_precision(struct bpf_verifier_env *env, const struct bpf_verifier_state *old)
{
    struct bpf_reg_state *state_reg;
    struct bpf_func_state *state;
    int i, err = 0;

    state = old->frame[old->curframe];
    state_reg = state->regs;
    for (i = 0; i < BPF_REG_FP; i++, state_reg++) {
        if (state_reg->type != SCALAR_VALUE || !state_reg->precise) {
            continue;
        }
        if (env->log.level & BPF_LOG_LEVEL2) {
            verbose(env, "propagating r%d\n", i);
        }
        err = mark_chain_precision(env, i);
        if (err < 0) {
            return err;
        }
    }

    for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
        if (state->stack[i].slot_type[0] != STACK_SPILL) {
            continue;
        }
        state_reg = &state->stack[i].spilled_ptr;
        if (state_reg->type != SCALAR_VALUE || !state_reg->precise) {
            continue;
        }
        if (env->log.level & BPF_LOG_LEVEL2) {
            verbose(env, "propagating fp%d\n", (-i - 1) * BPF_REG_SIZE);
        }
        err = mark_chain_precision_stack(env, i);
        if (err < 0) {
            return err;
        }
    }
    return 0;
}

static bool states_maybe_looping(struct bpf_verifier_state *old, struct bpf_verifier_state *cur)
{
    struct bpf_func_state *fold, *fcur;
    int i, fr = cur->curframe;

    if (old->curframe != fr) {
        return false;
    }

    fold = old->frame[fr];
    fcur = cur->frame[fr];
    for (i = 0; i < MAX_BPF_REG; i++) {
        if (memcmp(&fold->regs[i], &fcur->regs[i], offsetof(struct bpf_reg_state, parent))) {
            return false;
        }
    }
    return true;
}

static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
{
    struct bpf_verifier_state_list *new_sl;
    struct bpf_verifier_state_list *sl, **pprev;
    struct bpf_verifier_state *cur = env->cur_state, *new;
    int i, j, err, states_cnt = 0;
    bool add_new_state = env->test_state_freq ? true : false;

    cur->last_insn_idx = env->prev_insn_idx;
    if (!env->insn_aux_data[insn_idx].prune_point) {
        /* this 'insn_idx' instruction wasn't marked, so we will not
         * be doing state search here
         */
        return 0;
    }

    /* bpf progs typically have pruning point every 4 instructions
     * http://vger.kernel.org/bpfconf2019.html#session-1
     * Do not add new state for future pruning if the verifier hasn't seen
     * at least 2 jumps and at least 8 instructions.
     * This heuristics helps decrease 'total_states' and 'peak_states' metric.
     * In tests that amounts to up to 50% reduction into total verifier
     * memory consumption and 20% verifier time speedup.
     */
    if (env->jmps_processed - env->prev_jmps_processed >= 2 && env->insn_processed - env->prev_insn_processed >= 8) {
        add_new_state = true;
    }

    pprev = explored_state(env, insn_idx);
    sl = *pprev;

    clean_live_states(env, insn_idx, cur);

    while (sl) {
        states_cnt++;
        if (sl->state.insn_idx != insn_idx) {
            goto next;
        }
        if (sl->state.branches) {
            if (states_maybe_looping(&sl->state, cur) && states_equal(env, &sl->state, cur)) {
                verbose_linfo(env, insn_idx, "; ");
                verbose(env, "infinite loop detected at insn %d\n", insn_idx);
                return -EINVAL;
            }
            /* if the verifier is processing a loop, avoid adding new state
             * too often, since different loop iterations have distinct
             * states and may not help future pruning.
             * This threshold shouldn't be too low to make sure that
             * a loop with large bound will be rejected quickly.
             * The most abusive loop will be:
             * r1 += 1
             * if r1 < 1000000 goto pc-2
             * 1M insn_procssed limit / 100 == 10k peak states.
             * This threshold shouldn't be too high either, since states
             * at the end of the loop are likely to be useful in pruning.
             */
            if (env->jmps_processed - env->prev_jmps_processed < 20 &&
                env->insn_processed - env->prev_insn_processed < 100) {
                add_new_state = false;
            }
            goto miss;
        }
        if (states_equal(env, &sl->state, cur)) {
            sl->hit_cnt++;
            /* reached equivalent register/stack state,
             * prune the search.
             * Registers read by the continuation are read by us.
             * If we have any write marks in env->cur_state, they
             * will prevent corresponding reads in the continuation
             * from reaching our parent (an explored_state).  Our
             * own state will get the read marks recorded, but
             * they'll be immediately forgotten as we're pruning
             * this state and will pop a new one.
             */
            err = propagate_liveness(env, &sl->state, cur);

            /* if previous state reached the exit with precision and
             * current state is equivalent to it (except precsion marks)
             * the precision needs to be propagated back in
             * the current state.
             */
            err = err ?: push_jmp_history(env, cur);
            err = err ?: propagate_precision(env, &sl->state);
            if (err) {
                return err;
            }
            return 1;
        }
    miss:
        /* when new state is not going to be added do not increase miss count.
         * Otherwise several loop iterations will remove the state
         * recorded earlier. The goal of these heuristics is to have
         * states from some iterations of the loop (some in the beginning
         * and some at the end) to help pruning.
         */
        if (add_new_state) {
            sl->miss_cnt++;
        }
        /* heuristic to determine whether this state is beneficial
         * to keep checking from state equivalence point of view.
         * Higher numbers increase max_states_per_insn and verification time,
         * but do not meaningfully decrease insn_processed.
         */
        if (sl->miss_cnt > sl->hit_cnt * 3 + 3) {
            /* the state is unlikely to be useful. Remove it to
             * speed up verification
             */
            *pprev = sl->next;
            if (sl->state.frame[0]->regs[0].live & REG_LIVE_DONE) {
                u32 br = sl->state.branches;

                WARN_ONCE(br, "BUG live_done but branches_to_explore %d\n", br);
                free_verifier_state(&sl->state, false);
                kfree(sl);
                env->peak_states--;
            } else {
                /* cannot free this state, since parentage chain may
                 * walk it later. Add it for free_list instead to
                 * be freed at the end of verification
                 */
                sl->next = env->free_list;
                env->free_list = sl;
            }
            sl = *pprev;
            continue;
        }
    next:
        pprev = &sl->next;
        sl = *pprev;
    }

    if (env->max_states_per_insn < states_cnt) {
        env->max_states_per_insn = states_cnt;
    }

    if (!env->bpf_capable && states_cnt > BPF_COMPLEXITY_LIMIT_STATES) {
        return push_jmp_history(env, cur);
    }

    if (!add_new_state) {
        return push_jmp_history(env, cur);
    }

    /* There were no equivalent states, remember the current one.
     * Technically the current state is not proven to be safe yet,
     * but it will either reach outer most bpf_exit (which means it's safe)
     * or it will be rejected. When there are no loops the verifier won't be
     * seeing this tuple (frame[0].callsite, frame[1].callsite, .. insn_idx)
     * again on the way to bpf_exit.
     * When looping the sl->state.branches will be > 0 and this state
     * will not be considered for equivalence until branches == 0.
     */
    new_sl = kzalloc(sizeof(struct bpf_verifier_state_list), GFP_KERNEL);
    if (!new_sl) {
        return -ENOMEM;
    }
    env->total_states++;
    env->peak_states++;
    env->prev_jmps_processed = env->jmps_processed;
    env->prev_insn_processed = env->insn_processed;

    /* add new state to the head of linked list */
    new = &new_sl->state;
    err = copy_verifier_state(new, cur);
    if (err) {
        free_verifier_state(new, false);
        kfree(new_sl);
        return err;
    }
    new->insn_idx = insn_idx;
    WARN_ONCE(new->branches != 1, "BUG is_state_visited:branches_to_explore=%d insn %d\n", new->branches, insn_idx);

    cur->parent = new;
    cur->first_insn_idx = insn_idx;
    clear_jmp_history(cur);
    new_sl->next = *explored_state(env, insn_idx);
    *explored_state(env, insn_idx) = new_sl;
    /* connect new state to parentage chain. Current frame needs all
     * registers connected. Only r6 - r9 of the callers are alive (pushed
     * to the stack implicitly by JITs) so in callers' frames connect just
     * r6 - r9 as an optimization. Callers will have r1 - r5 connected to
     * the state of the call instruction (with WRITTEN set), and r0 comes
     * from callee with its full parentage chain, anyway.
     */
    /* clear write marks in current state: the writes we did are not writes
     * our child did, so they don't screen off its reads from us.
     * (There are no read marks in current state, because reads always mark
     * their parent and current state never has children yet.  Only
     * explored_states can get read marks.)
     */
    for (j = 0; j <= cur->curframe; j++) {
        for (i = j < cur->curframe ? BPF_REG_6 : 0; i < BPF_REG_FP; i++) {
            cur->frame[j]->regs[i].parent = &new->frame[j]->regs[i];
        }
        for (i = 0; i < BPF_REG_FP; i++) {
            cur->frame[j]->regs[i].live = REG_LIVE_NONE;
        }
    }

    /* all stack frames are accessible from callee, clear them all */
    for (j = 0; j <= cur->curframe; j++) {
        struct bpf_func_state *frame = cur->frame[j];
        struct bpf_func_state *newframe = new->frame[j];

        for (i = 0; i < frame->allocated_stack / BPF_REG_SIZE; i++) {
            frame->stack[i].spilled_ptr.live = REG_LIVE_NONE;
            frame->stack[i].spilled_ptr.parent = &newframe->stack[i].spilled_ptr;
        }
    }
    return 0;
}

/* Return true if it's OK to have the same insn return a different type. */
static bool reg_type_mismatch_ok(enum bpf_reg_type type)
{
    switch (base_type(type)) {
        case PTR_TO_CTX:
        case PTR_TO_SOCKET:
        case PTR_TO_SOCK_COMMON:
        case PTR_TO_TCP_SOCK:
        case PTR_TO_XDP_SOCK:
        case PTR_TO_BTF_ID:
            return false;
        default:
            return true;
    }
}

/* If an instruction was previously used with particular pointer types, then we
 * need to be careful to avoid cases such as the below, where it may be ok
 * for one branch accessing the pointer, but not ok for the other branch:
 *
 * R1 = sock_ptr
 * goto X;
 * ...
 * R1 = some_other_valid_ptr;
 * goto X;
 * ...
 * R2 = *(u32 *)(R1 + 0);
 */
static bool reg_type_mismatch(enum bpf_reg_type src, enum bpf_reg_type prev)
{
    return src != prev && (!reg_type_mismatch_ok(src) || !reg_type_mismatch_ok(prev));
}

static int do_check(struct bpf_verifier_env *env)
{
    bool pop_log = !(env->log.level & BPF_LOG_LEVEL2);
    struct bpf_verifier_state *state = env->cur_state;
    struct bpf_insn *insns = env->prog->insnsi;
    struct bpf_reg_state *regs;
    int insn_cnt = env->prog->len;
    bool do_print_state = false;
    int prev_insn_idx = -1;

    for (;;) {
        struct bpf_insn *insn;
        u8 class;
        int err;

        env->prev_insn_idx = prev_insn_idx;
        if (env->insn_idx >= insn_cnt) {
            verbose(env, "invalid insn idx %d insn_cnt %d\n", env->insn_idx, insn_cnt);
            return -EFAULT;
        }

        insn = &insns[env->insn_idx];
        class = BPF_CLASS(insn->code);

        if (++env->insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) {
            verbose(env, "BPF program is too large. Processed %d insn\n", env->insn_processed);
            return -E2BIG;
        }

        err = is_state_visited(env, env->insn_idx);
        if (err < 0) {
            return err;
        }
        if (err == 1) {
            /* found equivalent state, can prune the search */
            if (env->log.level & BPF_LOG_LEVEL) {
                if (do_print_state) {
                    verbose(env, "\nfrom %d to %d%s: safe\n", env->prev_insn_idx, env->insn_idx,
                            env->cur_state->speculative ? " (speculative execution)" : "");
                } else {
                    verbose(env, "%d: safe\n", env->insn_idx);
                }
            }
            goto process_bpf_exit;
        }

        if (signal_pending(current)) {
            return -EAGAIN;
        }

        if (need_resched()) {
            cond_resched();
        }

        if ((env->log.level & BPF_LOG_LEVEL2) || ((env->log.level & BPF_LOG_LEVEL) && do_print_state)) {
            if (env->log.level & BPF_LOG_LEVEL2) {
                verbose(env, "%d:", env->insn_idx);
            } else {
                verbose(env, "\nfrom %d to %d%s:", env->prev_insn_idx, env->insn_idx,
                        env->cur_state->speculative ? " (speculative execution)" : "");
            }
            print_verifier_state(env, state->frame[state->curframe]);
            do_print_state = false;
        }

        if (env->log.level & BPF_LOG_LEVEL) {
            const struct bpf_insn_cbs cbs = {
                .cb_print = verbose,
                .private_data = env,
            };

            verbose_linfo(env, env->insn_idx, "; ");
            verbose(env, "%d: ", env->insn_idx);
            print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
        }

        if (bpf_prog_is_dev_bound(env->prog->aux)) {
            err = bpf_prog_offload_verify_insn(env, env->insn_idx, env->prev_insn_idx);
            if (err) {
                return err;
            }
        }

        regs = cur_regs(env);
        sanitize_mark_insn_seen(env);
        prev_insn_idx = env->insn_idx;

        if (class == BPF_ALU || class == BPF_ALU64) {
            err = check_alu_op(env, insn);
            if (err) {
                return err;
            }
        } else if (class == BPF_LDX) {
            enum bpf_reg_type *prev_src_type, src_reg_type;

            /* check for reserved fields is already done */

            /* check src operand */
            err = check_reg_arg(env, insn->src_reg, SRC_OP);
            if (err) {
                return err;
            }

            err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
            if (err) {
                return err;
            }

            src_reg_type = regs[insn->src_reg].type;

            /* check that memory (src_reg + off) is readable,
             * the state of dst_reg will be updated by this func
             */
            err = check_mem_access(env, env->insn_idx, insn->src_reg, insn->off, BPF_SIZE(insn->code), BPF_READ,
                                   insn->dst_reg, false);
            if (err) {
                return err;
            }

            prev_src_type = &env->insn_aux_data[env->insn_idx].ptr_type;

            if (*prev_src_type == NOT_INIT) {
                /* saw a valid insn
                 * dst_reg = *(u32 *)(src_reg + off)
                 * save type to validate intersecting paths
                 */
                *prev_src_type = src_reg_type;
            } else if (reg_type_mismatch(src_reg_type, *prev_src_type)) {
                /* ABuser program is trying to use the same insn
                 * dst_reg = *(u32*) (src_reg + off)
                 * with different pointer types:
                 * src_reg == ctx in one branch and
                 * src_reg == stack|map in some other branch.
                 * Reject it.
                 */
                verbose(env, "same insn cannot be used with different pointers\n");
                return -EINVAL;
            }
        } else if (class == BPF_STX) {
            enum bpf_reg_type *prev_dst_type, dst_reg_type;
            if (BPF_MODE(insn->code) == BPF_XADD) {
                err = check_xadd(env, env->insn_idx, insn);
                if (err) {
                    return err;
                }
                env->insn_idx++;
                continue;
            }

            /* check src1 operand */
            err = check_reg_arg(env, insn->src_reg, SRC_OP);
            if (err) {
                return err;
            }
            /* check src2 operand */
            err = check_reg_arg(env, insn->dst_reg, SRC_OP);
            if (err) {
                return err;
            }

            dst_reg_type = regs[insn->dst_reg].type;

            /* check that memory (dst_reg + off) is writeable */
            err = check_mem_access(env, env->insn_idx, insn->dst_reg, insn->off, BPF_SIZE(insn->code), BPF_WRITE,
                                   insn->src_reg, false);
            if (err) {
                return err;
            }

            prev_dst_type = &env->insn_aux_data[env->insn_idx].ptr_type;

            if (*prev_dst_type == NOT_INIT) {
                *prev_dst_type = dst_reg_type;
            } else if (reg_type_mismatch(dst_reg_type, *prev_dst_type)) {
                verbose(env, "same insn cannot be used with different pointers\n");
                return -EINVAL;
            }
        } else if (class == BPF_ST) {
            if (BPF_MODE(insn->code) != BPF_MEM || insn->src_reg != BPF_REG_0) {
                verbose(env, "BPF_ST uses reserved fields\n");
                return -EINVAL;
            }
            /* check src operand */
            err = check_reg_arg(env, insn->dst_reg, SRC_OP);
            if (err) {
                return err;
            }
            if (is_ctx_reg(env, insn->dst_reg)) {
                verbose(env, "BPF_ST stores into R%d %s is not allowed\n", insn->dst_reg,
                        reg_type_str(env, reg_state(env, insn->dst_reg)->type));
                return -EACCES;
            }

            /* check that memory (dst_reg + off) is writeable */
            err = check_mem_access(env, env->insn_idx, insn->dst_reg, insn->off, BPF_SIZE(insn->code), BPF_WRITE, -1,
                                   false);
            if (err) {
                return err;
            }
        } else if (class == BPF_JMP || class == BPF_JMP32) {
            u8 opcode = BPF_OP(insn->code);
            env->jmps_processed++;
            if (opcode == BPF_CALL) {
                if (BPF_SRC(insn->code) != BPF_K || insn->off != 0 ||
                    (insn->src_reg != BPF_REG_0 && insn->src_reg != BPF_PSEUDO_CALL) || insn->dst_reg != BPF_REG_0 ||
                    class == BPF_JMP32) {
                    verbose(env, "BPF_CALL uses reserved fields\n");
                    return -EINVAL;
                }

                if (env->cur_state->active_spin_lock &&
                    (insn->src_reg == BPF_PSEUDO_CALL || insn->imm != BPF_FUNC_spin_unlock)) {
                    verbose(env, "function calls are not allowed while holding a lock\n");
                    return -EINVAL;
                }
                if (insn->src_reg == BPF_PSEUDO_CALL) {
                    err = check_func_call(env, insn, &env->insn_idx);
                } else {
                    err = check_helper_call(env, insn->imm, env->insn_idx);
                }
                if (err) {
                    return err;
                }
            } else if (opcode == BPF_JA) {
                if (BPF_SRC(insn->code) != BPF_K || insn->imm != 0 || insn->src_reg != BPF_REG_0 ||
                    insn->dst_reg != BPF_REG_0 || class == BPF_JMP32) {
                    verbose(env, "BPF_JA uses reserved fields\n");
                    return -EINVAL;
                }
                env->insn_idx += insn->off + 1;
                continue;
            } else if (opcode == BPF_EXIT) {
                if (BPF_SRC(insn->code) != BPF_K || insn->imm != 0 || insn->src_reg != BPF_REG_0 ||
                    insn->dst_reg != BPF_REG_0 || class == BPF_JMP32) {
                    verbose(env, "BPF_EXIT uses reserved fields\n");
                    return -EINVAL;
                }
                if (env->cur_state->active_spin_lock) {
                    verbose(env, "bpf_spin_unlock is missing\n");
                    return -EINVAL;
                }
                if (state->curframe) {
                    /* exit from nested function */
                    err = prepare_func_exit(env, &env->insn_idx);
                    if (err) {
                        return err;
                    }
                    do_print_state = true;
                    continue;
                }

                err = check_reference_leak(env);
                if (err) {
                    return err;
                }

                err = check_return_code(env);
                if (err) {
                    return err;
                }
            process_bpf_exit:
                update_branch_counts(env, env->cur_state);
                err = pop_stack(env, &prev_insn_idx, &env->insn_idx, pop_log);
                if (err < 0) {
                    if (err != -ENOENT) {
                        return err;
                    }
                    break;
                } else {
                    do_print_state = true;
                    continue;
                }
            } else {
                err = check_cond_jmp_op(env, insn, &env->insn_idx);
                if (err) {
                    return err;
                }
            }
        } else if (class == BPF_LD) {
            u8 mode = BPF_MODE(insn->code);
            if (mode == BPF_ABS || mode == BPF_IND) {
                err = check_ld_abs(env, insn);
                if (err) {
                    return err;
                }
            } else if (mode == BPF_IMM) {
                err = check_ld_imm(env, insn);
                if (err) {
                    return err;
                }
                env->insn_idx++;
                sanitize_mark_insn_seen(env);
            } else {
                verbose(env, "invalid BPF_LD mode\n");
                return -EINVAL;
            }
        } else {
            verbose(env, "unknown insn class %d\n", class);
            return -EINVAL;
        }
        env->insn_idx++;
    }

    return 0;
}

/* replace pseudo btf_id with kernel symbol address */
static int check_pseudo_btf_id(struct bpf_verifier_env *env, struct bpf_insn *insn, struct bpf_insn_aux_data *aux)
{
    const struct btf_var_secinfo *vsi;
    const struct btf_type *datasec;
    const struct btf_type *t;
    const char *sym_name;
    bool percpu = false;
    u32 type, id = insn->imm;
    s32 datasec_id;
    u64 addr;
    int i;

    if (!btf_vmlinux) {
        verbose(env, "kernel is missing BTF, make sure CONFIG_DEBUG_INFO_BTF=y is specified in Kconfig.\n");
        return -EINVAL;
    }

    if (insn[1].imm != 0) {
        verbose(env, "reserved field (insn[1].imm) is used in pseudo_btf_id ldimm64 insn.\n");
        return -EINVAL;
    }

    t = btf_type_by_id(btf_vmlinux, id);
    if (!t) {
        verbose(env, "ldimm64 insn specifies invalid btf_id %d.\n", id);
        return -ENOENT;
    }

    if (!btf_type_is_var(t)) {
        verbose(env, "pseudo btf_id %d in ldimm64 isn't KIND_VAR.\n", id);
        return -EINVAL;
    }

    sym_name = btf_name_by_offset(btf_vmlinux, t->name_off);
    addr = kallsyms_lookup_name(sym_name);
    if (!addr) {
        verbose(env, "ldimm64 failed to find the address for kernel symbol '%s'.\n", sym_name);
        return -ENOENT;
    }

    datasec_id = btf_find_by_name_kind(btf_vmlinux, ".data..percpu", BTF_KIND_DATASEC);
    if (datasec_id > 0) {
        datasec = btf_type_by_id(btf_vmlinux, datasec_id);
        for_each_vsi(i, datasec, vsi)
        {
            if (vsi->type == id) {
                percpu = true;
                break;
            }
        }
    }

    insn[0].imm = (u32)addr;
    insn[1].imm = addr >> VERIFIER_THIRTYTWO;

    type = t->type;
    t = btf_type_skip_modifiers(btf_vmlinux, type, NULL);
    if (percpu) {
        aux->btf_var.reg_type = PTR_TO_PERCPU_BTF_ID;
        aux->btf_var.btf_id = type;
    } else if (!btf_type_is_struct(t)) {
        const struct btf_type *ret;
        const char *tname;
        u32 tsize;

        /* resolve the type size of ksym. */
        ret = btf_resolve_size(btf_vmlinux, t, &tsize);
        if (IS_ERR(ret)) {
            tname = btf_name_by_offset(btf_vmlinux, t->name_off);
            verbose(env, "ldimm64 unable to resolve the size of type '%s': %ld\n", tname, PTR_ERR(ret));
            return -EINVAL;
        }
        aux->btf_var.reg_type = PTR_TO_MEM | MEM_RDONLY;
        aux->btf_var.mem_size = tsize;
    } else {
        aux->btf_var.reg_type = PTR_TO_BTF_ID;
        aux->btf_var.btf_id = type;
    }
    return 0;
}

static int check_map_prealloc(struct bpf_map *map)
{
    return (map->map_type != BPF_MAP_TYPE_HASH && map->map_type != BPF_MAP_TYPE_PERCPU_HASH &&
            map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS) ||
           !(map->map_flags & BPF_F_NO_PREALLOC);
}

static bool is_tracing_prog_type(enum bpf_prog_type type)
{
    switch (type) {
        case BPF_PROG_TYPE_KPROBE:
        case BPF_PROG_TYPE_TRACEPOINT:
        case BPF_PROG_TYPE_PERF_EVENT:
        case BPF_PROG_TYPE_RAW_TRACEPOINT:
            return true;
        default:
            return false;
    }
}

static bool is_preallocated_map(struct bpf_map *map)
{
    if (!check_map_prealloc(map)) {
        return false;
    }
    if (map->inner_map_meta && !check_map_prealloc(map->inner_map_meta)) {
        return false;
    }
    return true;
}

static int check_map_prog_compatibility(struct bpf_verifier_env *env, struct bpf_map *map, struct bpf_prog *prog)

{
    enum bpf_prog_type prog_type = resolve_prog_type(prog);
    /*
     * Validate that trace type programs use preallocated hash maps.
     *
     * For programs attached to PERF events this is mandatory as the
     * perf NMI can hit any arbitrary code sequence.
     *
     * All other trace types using preallocated hash maps are unsafe as
     * well because tracepoint or kprobes can be inside locked regions
     * of the memory allocator or at a place where a recursion into the
     * memory allocator would see inconsistent state.
     *
     * On RT enabled kernels run-time allocation of all trace type
     * programs is strictly prohibited due to lock type constraints. On
     * !RT kernels it is allowed for backwards compatibility reasons for
     * now, but warnings are emitted so developers are made aware of
     * the unsafety and can fix their programs before this is enforced.
     */
    if (is_tracing_prog_type(prog_type) && !is_preallocated_map(map)) {
        if (prog_type == BPF_PROG_TYPE_PERF_EVENT) {
            verbose(env, "perf_event programs can only use preallocated hash map\n");
            return -EINVAL;
        }
        if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
            verbose(env, "trace type programs can only use preallocated hash map\n");
            return -EINVAL;
        }
        WARN_ONCE(1, "trace type BPF program uses run-time allocation\n");
        verbose(
            env,
            "trace type programs with run-time allocated hash maps are unsafe. Switch to preallocated hash maps.\n");
    }

    if ((is_tracing_prog_type(prog_type) || prog_type == BPF_PROG_TYPE_SOCKET_FILTER) && map_value_has_spin_lock(map)) {
        verbose(env, "tracing progs cannot use bpf_spin_lock yet\n");
        return -EINVAL;
    }

    if ((bpf_prog_is_dev_bound(prog->aux) || bpf_map_is_dev_bound(map)) && !bpf_offload_prog_map_match(prog, map)) {
        verbose(env, "offload device mismatch between prog and map\n");
        return -EINVAL;
    }

    if (map->map_type == BPF_MAP_TYPE_STRUCT_OPS) {
        verbose(env, "bpf_struct_ops map cannot be used in prog\n");
        return -EINVAL;
    }

    if (prog->aux->sleepable) {
        switch (map->map_type) {
            case BPF_MAP_TYPE_HASH:
            case BPF_MAP_TYPE_LRU_HASH:
            case BPF_MAP_TYPE_ARRAY:
                if (!is_preallocated_map(map)) {
                    verbose(env, "Sleepable programs can only use preallocated hash maps\n");
                    return -EINVAL;
                }
                break;
            default:
                verbose(env, "Sleepable programs can only use array and hash maps\n");
                return -EINVAL;
        }
    }

    return 0;
}

static bool bpf_map_is_cgroup_storage(struct bpf_map *map)
{
    return (map->map_type == BPF_MAP_TYPE_CGROUP_STORAGE || map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE);
}

/* find and rewrite pseudo imm in ld_imm64 instructions:
 *
 * 1. if it accesses map FD, replace it with actual map pointer.
 * 2. if it accesses btf_id of a VAR, replace it with pointer to the var.
 *
 * NOTE: btf_vmlinux is required for converting pseudo btf_id.
 */
static int resolve_pseudo_ldimm64(struct bpf_verifier_env *env)
{
    struct bpf_insn *insn = env->prog->insnsi;
    int insn_cnt = env->prog->len;
    int i, j, err;

    err = bpf_prog_calc_tag(env->prog);
    if (err) {
        return err;
    }

    for (i = 0; i < insn_cnt; i++, insn++) {
        if (BPF_CLASS(insn->code) == BPF_LDX && (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) {
            verbose(env, "BPF_LDX uses reserved fields\n");
            return -EINVAL;
        }

        if (BPF_CLASS(insn->code) == BPF_STX &&
            ((BPF_MODE(insn->code) != BPF_MEM && BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) {
            verbose(env, "BPF_STX uses reserved fields\n");
            return -EINVAL;
        }

        if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
            struct bpf_insn_aux_data *aux;
            struct bpf_map *map;
            struct fd f;
            u64 addr;

            if (i == insn_cnt - 1 || insn[1].code != 0 || insn[1].dst_reg != 0 || insn[1].src_reg != 0 ||
                insn[1].off != 0) {
                verbose(env, "invalid bpf_ld_imm64 insn\n");
                return -EINVAL;
            }

            if (insn[0].src_reg == 0) {
                /* valid generic load 64-bit imm */
                goto next_insn;
            }

            if (insn[0].src_reg == BPF_PSEUDO_BTF_ID) {
                aux = &env->insn_aux_data[i];
                err = check_pseudo_btf_id(env, insn, aux);
                if (err) {
                    return err;
                }
                goto next_insn;
            }

            /* In final convert_pseudo_ld_imm64() step, this is
             * converted into regular 64-bit imm load insn.
             */
            if ((insn[0].src_reg != BPF_PSEUDO_MAP_FD && insn[0].src_reg != BPF_PSEUDO_MAP_VALUE) ||
                (insn[0].src_reg == BPF_PSEUDO_MAP_FD && insn[1].imm != 0)) {
                verbose(env, "unrecognized bpf_ld_imm64 insn\n");
                return -EINVAL;
            }

            f = fdget(insn[0].imm);
            map = __bpf_map_get(f);
            if (IS_ERR(map)) {
                verbose(env, "fd %d is not pointing to valid bpf_map\n", insn[0].imm);
                return PTR_ERR(map);
            }

            err = check_map_prog_compatibility(env, map, env->prog);
            if (err) {
                fdput(f);
                return err;
            }

            aux = &env->insn_aux_data[i];
            if (insn->src_reg == BPF_PSEUDO_MAP_FD) {
                addr = (unsigned long)map;
            } else {
                u32 off = insn[1].imm;

                if (off >= BPF_MAX_VAR_OFF) {
                    verbose(env, "direct value offset of %u is not allowed\n", off);
                    fdput(f);
                    return -EINVAL;
                }

                if (!map->ops->map_direct_value_addr) {
                    verbose(env, "no direct value access support for this map type\n");
                    fdput(f);
                    return -EINVAL;
                }

                err = map->ops->map_direct_value_addr(map, &addr, off);
                if (err) {
                    verbose(env, "invalid access to map value pointer, value_size=%u off=%u\n", map->value_size, off);
                    fdput(f);
                    return err;
                }

                aux->map_off = off;
                addr += off;
            }

            insn[0].imm = (u32)addr;
            insn[1].imm = addr >> VERIFIER_THIRTYTWO;

            /* check whether we recorded this map already */
            for (j = 0; j < env->used_map_cnt; j++) {
                if (env->used_maps[j] == map) {
                    aux->map_index = j;
                    fdput(f);
                    goto next_insn;
                }
            }

            if (env->used_map_cnt >= MAX_USED_MAPS) {
                fdput(f);
                return -E2BIG;
            }

            /* hold the map. If the program is rejected by verifier,
             * the map will be released by release_maps() or it
             * will be used by the valid program until it's unloaded
             * and all maps are released in free_used_maps()
             */
            bpf_map_inc(map);

            aux->map_index = env->used_map_cnt;
            env->used_maps[env->used_map_cnt++] = map;

            if (bpf_map_is_cgroup_storage(map) && bpf_cgroup_storage_assign(env->prog->aux, map)) {
                verbose(env, "only one cgroup storage of each type is allowed\n");
                fdput(f);
                return -EBUSY;
            }

            fdput(f);
        next_insn:
            insn++;
            i++;
            continue;
        }

        /* Basic sanity check before we invest more work here. */
        if (!bpf_opcode_in_insntable(insn->code)) {
            verbose(env, "unknown opcode %02x\n", insn->code);
            return -EINVAL;
        }
    }

    /* now all pseudo BPF_LD_IMM64 instructions load valid
     * 'struct bpf_map *' into a register instead of user map_fd.
     * These pointers will be used later by verifier to validate map access.
     */
    return 0;
}

/* drop refcnt of maps used by the rejected program */
static void release_maps(struct bpf_verifier_env *env)
{
    __bpf_free_used_maps(env->prog->aux, env->used_maps, env->used_map_cnt);
}

/* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env)
{
    struct bpf_insn *insn = env->prog->insnsi;
    int insn_cnt = env->prog->len;
    int i;

    for (i = 0; i < insn_cnt; i++, insn++) {
        if (insn->code == (BPF_LD | BPF_IMM | BPF_DW)) {
            insn->src_reg = 0;
        }
    }
}

/* single env->prog->insni[off] instruction was replaced with the range
 * insni[off, off + cnt).  Adjust corresponding insn_aux_data by copying
 * [0, off) and [off, end) to new locations, so the patched range stays zero
 */
static void adjust_insn_aux_data(struct bpf_verifier_env *env, struct bpf_insn_aux_data *new_data,
                                 struct bpf_prog *new_prog, u32 off, u32 cnt)
{
    struct bpf_insn_aux_data *old_data = env->insn_aux_data;
    struct bpf_insn *insn = new_prog->insnsi;
    u32 old_seen = old_data[off].seen;
    u32 prog_len;
    int i;

    /* aux info at OFF always needs adjustment, no matter fast path
     * (cnt == 1) is taken or not. There is no guarantee INSN at OFF is the
     * original insn at old prog.
     */
    old_data[off].zext_dst = insn_has_def32(env, insn + off + cnt - 1);

    if (cnt == 1) {
        return;
    }
    prog_len = new_prog->len;

    memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off);
    memcpy(new_data + off + cnt - 1, old_data + off, sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1));
    for (i = off; i < off + cnt - 1; i++) {
        /* Expand insni[off]'s seen count to the patched range. */
        new_data[i].seen = old_seen;
        new_data[i].zext_dst = insn_has_def32(env, insn + i);
    }
    env->insn_aux_data = new_data;
    vfree(old_data);
}

static void adjust_subprog_starts(struct bpf_verifier_env *env, u32 off, u32 len)
{
    int i;

    if (len == 1) {
        return;
    }
    /* NOTE: fake 'exit' subprog should be updated as well. */
    for (i = 0; i <= env->subprog_cnt; i++) {
        if (env->subprog_info[i].start <= off) {
            continue;
        }
        env->subprog_info[i].start += len - 1;
    }
}

static void adjust_poke_descs(struct bpf_prog *prog, u32 off, u32 len)
{
    struct bpf_jit_poke_descriptor *tab = prog->aux->poke_tab;
    int i, sz = prog->aux->size_poke_tab;
    struct bpf_jit_poke_descriptor *desc;

    for (i = 0; i < sz; i++) {
        desc = &tab[i];
        if (desc->insn_idx <= off) {
            continue;
        }
        desc->insn_idx += len - 1;
    }
}

static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off, const struct bpf_insn *patch,
                                            u32 len)
{
    struct bpf_prog *new_prog;
    struct bpf_insn_aux_data *new_data = NULL;

    if (len > 1) {
        new_data = vzalloc(array_size(env->prog->len + len - 1, sizeof(struct bpf_insn_aux_data)));
        if (!new_data) {
            return NULL;
        }
    }

    new_prog = bpf_patch_insn_single(env->prog, off, patch, len);
    if (IS_ERR(new_prog)) {
        if (PTR_ERR(new_prog) == -ERANGE) {
            verbose(env, "insn %d cannot be patched due to 16-bit range\n", env->insn_aux_data[off].orig_idx);
        }
        vfree(new_data);
        return NULL;
    }
    adjust_insn_aux_data(env, new_data, new_prog, off, len);
    adjust_subprog_starts(env, off, len);
    adjust_poke_descs(new_prog, off, len);
    return new_prog;
}

static int adjust_subprog_starts_after_remove(struct bpf_verifier_env *env, u32 off, u32 cnt)
{
    int i, j;

    /* find first prog starting at or after off (first to remove) */
    for (i = 0; i < env->subprog_cnt; i++) {
        if (env->subprog_info[i].start >= off) {
            break;
        }
    }
    /* find first prog starting at or after off + cnt (first to stay) */
    for (j = i; j < env->subprog_cnt; j++) {
        if (env->subprog_info[j].start >= off + cnt) {
            break;
        }
    }
    /* if j doesn't start exactly at off + cnt, we are just removing
     * the front of previous prog
     */
    if (env->subprog_info[j].start != off + cnt) {
        j--;
    }

    if (j > i) {
        struct bpf_prog_aux *aux = env->prog->aux;
        int move;

        /* move fake 'exit' subprog as well */
        move = env->subprog_cnt + 1 - j;

        memmove(env->subprog_info + i, env->subprog_info + j, sizeof(*env->subprog_info) * move);
        env->subprog_cnt -= j - i;

        /* remove func_info */
        if (aux->func_info) {
            move = aux->func_info_cnt - j;

            memmove(aux->func_info + i, aux->func_info + j, sizeof(*aux->func_info) * move);
            aux->func_info_cnt -= j - i;
            /* func_info->insn_off is set after all code rewrites,
             * in adjust_btf_func() - no need to adjust
             */
        }
    } else {
        /* convert i from "first prog to remove" to "first to adjust" */
        if (env->subprog_info[i].start == off) {
            i++;
        }
    }

    /* update fake 'exit' subprog as well */
    for (; i <= env->subprog_cnt; i++) {
        env->subprog_info[i].start -= cnt;
    }

    return 0;
}

static int bpf_adj_linfo_after_remove(struct bpf_verifier_env *env, u32 off, u32 cnt)
{
    struct bpf_prog *prog = env->prog;
    u32 i, l_off, l_cnt, nr_linfo;
    struct bpf_line_info *linfo;

    nr_linfo = prog->aux->nr_linfo;
    if (!nr_linfo) {
        return 0;
    }

    linfo = prog->aux->linfo;

    /* find first line info to remove, count lines to be removed */
    for (i = 0; i < nr_linfo; i++) {
        if (linfo[i].insn_off >= off) {
            break;
        }
    }

    l_off = i;
    l_cnt = 0;
    for (; i < nr_linfo; i++) {
        if (linfo[i].insn_off < off + cnt) {
            l_cnt++;
        } else {
            break;
        }
    }

    /* First live insn doesn't match first live linfo, it needs to "inherit"
     * last removed linfo.  prog is already modified, so prog->len == off
     * means no live instructions after (tail of the program was removed).
     */
    if (prog->len != off && l_cnt && (i == nr_linfo || linfo[i].insn_off != off + cnt)) {
        l_cnt--;
        linfo[--i].insn_off = off + cnt;
    }

    /* remove the line info which refer to the removed instructions */
    if (l_cnt) {
        memmove(linfo + l_off, linfo + i, sizeof(*linfo) * (nr_linfo - i));

        prog->aux->nr_linfo -= l_cnt;
        nr_linfo = prog->aux->nr_linfo;
    }

    /* pull all linfo[i].insn_off >= off + cnt in by cnt */
    for (i = l_off; i < nr_linfo; i++) {
        linfo[i].insn_off -= cnt;
    }

    /* fix up all subprogs (incl. 'exit') which start >= off */
    for (i = 0; i <= env->subprog_cnt; i++) {
        if (env->subprog_info[i].linfo_idx > l_off) {
            /* program may have started in the removed region but
             * may not be fully removed
             */
            if (env->subprog_info[i].linfo_idx >= l_off + l_cnt) {
                env->subprog_info[i].linfo_idx -= l_cnt;
            } else {
                env->subprog_info[i].linfo_idx = l_off;
            }
        }
    }

    return 0;
}

static int verifier_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt)
{
    struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
    unsigned int orig_prog_len = env->prog->len;
    int err;

    if (bpf_prog_is_dev_bound(env->prog->aux)) {
        bpf_prog_offload_remove_insns(env, off, cnt);
    }

    err = bpf_remove_insns(env->prog, off, cnt);
    if (err) {
        return err;
    }

    err = adjust_subprog_starts_after_remove(env, off, cnt);
    if (err) {
        return err;
    }

    err = bpf_adj_linfo_after_remove(env, off, cnt);
    if (err) {
        return err;
    }

    memmove(aux_data + off, aux_data + off + cnt, sizeof(*aux_data) * (orig_prog_len - off - cnt));

    return 0;
}

/* The verifier does more data flow analysis than llvm and will not
 * explore branches that are dead at run time. Malicious programs can
 * have dead code too. Therefore replace all dead at-run-time code
 * with 'ja -1'.
 *
 * Just nops are not optimal, e.g. if they would sit at the end of the
 * program and through another bug we would manage to jump there, then
 * we'd execute beyond program memory otherwise. Returning exception
 * code also wouldn't work since we can have subprogs where the dead
 * code could be located.
 */
static void sanitize_dead_code(struct bpf_verifier_env *env)
{
    struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
    struct bpf_insn trap = BPF_JMP_IMM(BPF_JA, 0, 0, -1);
    struct bpf_insn *insn = env->prog->insnsi;
    const int insn_cnt = env->prog->len;
    int i;

    for (i = 0; i < insn_cnt; i++) {
        if (aux_data[i].seen) {
            continue;
        }
        memcpy(insn + i, &trap, sizeof(trap));
        aux_data[i].zext_dst = false;
    }
}

static bool insn_is_cond_jump(u8 code)
{
    u8 op;

    if (BPF_CLASS(code) == BPF_JMP32) {
        return true;
    }

    if (BPF_CLASS(code) != BPF_JMP) {
        return false;
    }

    op = BPF_OP(code);
    return op != BPF_JA && op != BPF_EXIT && op != BPF_CALL;
}

static void opt_hard_wire_dead_code_branches(struct bpf_verifier_env *env)
{
    struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
    struct bpf_insn ja = BPF_JMP_IMM(BPF_JA, 0, 0, 0);
    struct bpf_insn *insn = env->prog->insnsi;
    const int insn_cnt = env->prog->len;
    int i;

    for (i = 0; i < insn_cnt; i++, insn++) {
        if (!insn_is_cond_jump(insn->code)) {
            continue;
        }

        if (!aux_data[i + 1].seen) {
            ja.off = insn->off;
        } else if (!aux_data[i + 1 + insn->off].seen) {
            ja.off = 0;
        } else {
            continue;
        }

        if (bpf_prog_is_dev_bound(env->prog->aux)) {
            bpf_prog_offload_replace_insn(env, i, &ja);
        }

        memcpy(insn, &ja, sizeof(ja));
    }
}

static int opt_remove_dead_code(struct bpf_verifier_env *env)
{
    struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
    int insn_cnt = env->prog->len;
    int i, err;

    for (i = 0; i < insn_cnt; i++) {
        int j;

        j = 0;
        while (i + j < insn_cnt && !aux_data[i + j].seen) {
            j++;
        }
        if (!j) {
            continue;
        }

        err = verifier_remove_insns(env, i, j);
        if (err) {
            return err;
        }
        insn_cnt = env->prog->len;
    }

    return 0;
}

static int opt_remove_nops(struct bpf_verifier_env *env)
{
    const struct bpf_insn ja = BPF_JMP_IMM(BPF_JA, 0, 0, 0);
    struct bpf_insn *insn = env->prog->insnsi;
    int insn_cnt = env->prog->len;
    int i, err;

    for (i = 0; i < insn_cnt; i++) {
        if (memcmp(&insn[i], &ja, sizeof(ja))) {
            continue;
        }

        err = verifier_remove_insns(env, i, 1);
        if (err) {
            return err;
        }
        insn_cnt--;
        i--;
    }

    return 0;
}

static int opt_subreg_zext_lo32_rnd_hi32(struct bpf_verifier_env *env, const union bpf_attr *attr)
{
    struct bpf_insn *patch, zext_patch[2], rnd_hi32_patch[4];
    struct bpf_insn_aux_data *aux = env->insn_aux_data;
    int i, patch_len, delta = 0, len = env->prog->len;
    struct bpf_insn *insns = env->prog->insnsi;
    struct bpf_prog *new_prog;
    bool rnd_hi32;

    rnd_hi32 = attr->prog_flags & BPF_F_TEST_RND_HI32;
    zext_patch[1] = BPF_ZEXT_REG(0);
    rnd_hi32_patch[1] = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, 0);
    rnd_hi32_patch[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_AX, 32);
    rnd_hi32_patch[3] = BPF_ALU64_REG(BPF_OR, 0, BPF_REG_AX);
    for (i = 0; i < len; i++) {
        int adj_idx = i + delta;
        struct bpf_insn insn;

        insn = insns[adj_idx];
        if (!aux[adj_idx].zext_dst) {
            u8 code, class;
            u32 imm_rnd;

            if (!rnd_hi32) {
                continue;
            }

            code = insn.code;
            class = BPF_CLASS(code);
            if (insn_no_def(&insn)) {
                continue;
            }

            /* NOTE: arg "reg" (the fourth one) is only used for
             *       BPF_STX which has been ruled out in above
             *       check, it is safe to pass NULL here.
             */
            if (is_reg64(env, &insn, insn.dst_reg, NULL, DST_OP)) {
                if (class == BPF_LD && BPF_MODE(code) == BPF_IMM) {
                    i++;
                }
                continue;
            }

            /* ctx load could be transformed into wider load. */
            if (class == BPF_LDX && aux[adj_idx].ptr_type == PTR_TO_CTX) {
                continue;
            }

            imm_rnd = get_random_int();
            rnd_hi32_patch[0] = insn;
            rnd_hi32_patch[1].imm = imm_rnd;
            rnd_hi32_patch[3].dst_reg = insn.dst_reg;
            patch = rnd_hi32_patch;
            patch_len = VERIFIER_FOUR;
            goto apply_patch_buffer;
        }

        if (!bpf_jit_needs_zext()) {
            continue;
        }

        zext_patch[0] = insn;
        zext_patch[1].dst_reg = insn.dst_reg;
        zext_patch[1].src_reg = insn.dst_reg;
        patch = zext_patch;
        patch_len = 2;
    apply_patch_buffer:
        new_prog = bpf_patch_insn_data(env, adj_idx, patch, patch_len);
        if (!new_prog) {
            return -ENOMEM;
        }
        env->prog = new_prog;
        insns = new_prog->insnsi;
        aux = env->insn_aux_data;
        delta += patch_len - 1;
    }

    return 0;
}

/* convert load instructions that access fields of a context type into a
 * sequence of instructions that access fields of the underlying structure:
 *     struct __sk_buff    -> struct sk_buff
 *     struct bpf_sock_ops -> struct sock
 */
static int convert_ctx_accesses(struct bpf_verifier_env *env)
{
    const struct bpf_verifier_ops *ops = env->ops;
    int i, cnt, size, ctx_field_size, delta = 0;
    const int insn_cnt = env->prog->len;
    struct bpf_insn insn_buf[VERIFIER_SIXTEEN], *insn;
    u32 target_size, size_default, off;
    struct bpf_prog *new_prog;
    enum bpf_access_type type;
    bool is_narrower_load;

    if (ops->gen_prologue || env->seen_direct_write) {
        if (!ops->gen_prologue) {
            verbose(env, "bpf verifier is misconfigured\n");
            return -EINVAL;
        }
        cnt = ops->gen_prologue(insn_buf, env->seen_direct_write, env->prog);
        if (cnt >= ARRAY_SIZE(insn_buf)) {
            verbose(env, "bpf verifier is misconfigured\n");
            return -EINVAL;
        } else if (cnt) {
            new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt);
            if (!new_prog) {
                return -ENOMEM;
            }

            env->prog = new_prog;
            delta += cnt - 1;
        }
    }

    if (bpf_prog_is_dev_bound(env->prog->aux)) {
        return 0;
    }

    insn = env->prog->insnsi + delta;

    for (i = 0; i < insn_cnt; i++, insn++) {
        bpf_convert_ctx_access_t convert_ctx_access;
        bool ctx_access;

        if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) || insn->code == (BPF_LDX | BPF_MEM | BPF_H) ||
            insn->code == (BPF_LDX | BPF_MEM | BPF_W) || insn->code == (BPF_LDX | BPF_MEM | BPF_DW)) {
            type = BPF_READ;
            ctx_access = true;
        } else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) || insn->code == (BPF_STX | BPF_MEM | BPF_H) ||
                   insn->code == (BPF_STX | BPF_MEM | BPF_W) || insn->code == (BPF_STX | BPF_MEM | BPF_DW) ||
                   insn->code == (BPF_ST | BPF_MEM | BPF_B) || insn->code == (BPF_ST | BPF_MEM | BPF_H) ||
                   insn->code == (BPF_ST | BPF_MEM | BPF_W) || insn->code == (BPF_ST | BPF_MEM | BPF_DW)) {
            type = BPF_WRITE;
            ctx_access = BPF_CLASS(insn->code) == BPF_STX;
        } else {
            continue;
        }

        if (type == BPF_WRITE && env->insn_aux_data[i + delta].sanitize_stack_spill) {
            struct bpf_insn patch[] = {
                *insn,
                BPF_ST_NOSPEC(),
            };

            cnt = ARRAY_SIZE(patch);
            new_prog = bpf_patch_insn_data(env, i + delta, patch, cnt);
            if (!new_prog) {
                return -ENOMEM;
            }

            delta += cnt - 1;
            env->prog = new_prog;
            insn = new_prog->insnsi + i + delta;
            continue;
        }

        if (!ctx_access) {
            continue;
        }

        switch (env->insn_aux_data[i + delta].ptr_type) {
            case PTR_TO_CTX:
                if (!ops->convert_ctx_access) {
                    continue;
                }
                convert_ctx_access = ops->convert_ctx_access;
                break;
            case PTR_TO_SOCKET:
            case PTR_TO_SOCK_COMMON:
                convert_ctx_access = bpf_sock_convert_ctx_access;
                break;
            case PTR_TO_TCP_SOCK:
                convert_ctx_access = bpf_tcp_sock_convert_ctx_access;
                break;
            case PTR_TO_XDP_SOCK:
                convert_ctx_access = bpf_xdp_sock_convert_ctx_access;
                break;
            case PTR_TO_BTF_ID:
                if (type == BPF_READ) {
                    insn->code = BPF_LDX | BPF_PROBE_MEM | BPF_SIZE((insn)->code);
                    env->prog->aux->num_exentries++;
                } else if (resolve_prog_type(env->prog) != BPF_PROG_TYPE_STRUCT_OPS) {
                    verbose(env, "Writes through BTF pointers are not allowed\n");
                    return -EINVAL;
                }
                continue;
            default:
                continue;
        }

        ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size;
        size = BPF_LDST_BYTES(insn);

        /* If the read access is a narrower load of the field,
         * convert to a 4/8-byte load, to minimum program type specific
         * convert_ctx_access changes. If conversion is successful,
         * we will apply proper mask to the result.
         */
        is_narrower_load = size < ctx_field_size;
        size_default = bpf_ctx_off_adjust_machine(ctx_field_size);
        off = insn->off;
        if (is_narrower_load) {
            u8 size_code;

            if (type == BPF_WRITE) {
                verbose(env, "bpf verifier narrow ctx access misconfigured\n");
                return -EINVAL;
            }

            size_code = BPF_H;
            if (ctx_field_size == VERIFIER_FOUR) {
                size_code = BPF_W;
            } else if (ctx_field_size == VERIFIER_EIGHT) {
                size_code = BPF_DW;
            }

            insn->off = off & ~(size_default - 1);
            insn->code = BPF_LDX | BPF_MEM | size_code;
        }

        target_size = 0;
        cnt = convert_ctx_access(type, insn, insn_buf, env->prog, &target_size);
        if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) || (ctx_field_size && !target_size)) {
            verbose(env, "bpf verifier is misconfigured\n");
            return -EINVAL;
        }

        if (is_narrower_load && size < target_size) {
            u8 shift = bpf_ctx_narrow_access_offset(off, size, size_default) * VERIFIER_EIGHT;
            if (shift && cnt + 1 >= ARRAY_SIZE(insn_buf)) {
                verbose(env, "bpf verifier narrow ctx load misconfigured\n");
                return -EINVAL;
            }
            if (ctx_field_size <= VERIFIER_FOUR) {
                if (shift) {
                    insn_buf[cnt++] = BPF_ALU32_IMM(BPF_RSH, insn->dst_reg, shift);
                }
                insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg, ((1 << size) * VERIFIER_EIGHT) - 1);
            } else {
                if (shift) {
                    insn_buf[cnt++] = BPF_ALU64_IMM(BPF_RSH, insn->dst_reg, shift);
                }
                insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg, ((1ULL << size) * VERIFIER_EIGHT) - 1);
            }
        }

        new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
        if (!new_prog) {
            return -ENOMEM;
        }

        delta += cnt - 1;

        /* keep walking new program and skip insns we just inserted */
        env->prog = new_prog;
        insn = new_prog->insnsi + i + delta;
    }

    return 0;
}

static int jit_subprogs(struct bpf_verifier_env *env)
{
    struct bpf_prog *prog = env->prog, **func, *tmp;
    int i, j, subprog_start, subprog_end = 0, len, subprog;
    struct bpf_map *map_ptr;
    struct bpf_insn *insn;
    void *old_bpf_func;
    int err, num_exentries;

    if (env->subprog_cnt <= 1) {
        return 0;
    }

    for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
        if (insn->code != (BPF_JMP | BPF_CALL) || insn->src_reg != BPF_PSEUDO_CALL) {
            continue;
        }
        /* Upon error here we cannot fall back to interpreter but
         * need a hard reject of the program. Thus -EFAULT is
         * propagated in any case.
         */
        subprog = find_subprog(env, i + insn->imm + 1);
        if (subprog < 0) {
            WARN_ONCE(1, "verifier bug. No program starts at insn %d\n", i + insn->imm + 1);
            return -EFAULT;
        }
        /* temporarily remember subprog id inside insn instead of
         * aux_data, since next loop will split up all insns into funcs
         */
        insn->off = subprog;
        /* remember original imm in case JIT fails and fallback
         * to interpreter will be needed
         */
        env->insn_aux_data[i].call_imm = insn->imm;
        /* point imm to __bpf_call_base+1 from JITs point of view */
        insn->imm = 1;
    }

    err = bpf_prog_alloc_jited_linfo(prog);
    if (err) {
        goto out_undo_insn;
    }

    err = -ENOMEM;
    func = kcalloc(env->subprog_cnt, sizeof(prog), GFP_KERNEL);
    if (!func) {
        goto out_undo_insn;
    }

    for (i = 0; i < env->subprog_cnt; i++) {
        subprog_start = subprog_end;
        subprog_end = env->subprog_info[i + 1].start;

        len = subprog_end - subprog_start;
        /* BPF_PROG_RUN doesn't call subprogs directly,
         * hence main prog stats include the runtime of subprogs.
         * subprogs don't have IDs and not reachable via prog_get_next_id
         * func[i]->aux->stats will never be accessed and stays NULL
         */
        func[i] = bpf_prog_alloc_no_stats(bpf_prog_size(len), GFP_USER);
        if (!func[i]) {
            goto out_free;
        }
        memcpy(func[i]->insnsi, &prog->insnsi[subprog_start], len * sizeof(struct bpf_insn));
        func[i]->type = prog->type;
        func[i]->len = len;
        if (bpf_prog_calc_tag(func[i])) {
            goto out_free;
        }
        func[i]->is_func = 1;
        func[i]->aux->func_idx = i;
        /* Below members will be freed only at prog->aux */
        func[i]->aux->btf = prog->aux->btf;
        func[i]->aux->func_info = prog->aux->func_info;
        func[i]->aux->poke_tab = prog->aux->poke_tab;
        func[i]->aux->size_poke_tab = prog->aux->size_poke_tab;

        for (j = 0; j < prog->aux->size_poke_tab; j++) {
            struct bpf_jit_poke_descriptor *poke;

            poke = &prog->aux->poke_tab[j];
            if (poke->insn_idx < subprog_end && poke->insn_idx >= subprog_start) {
                poke->aux = func[i]->aux;
            }
        }

        /* Use bpf_prog_F_tag to indicate functions in stack traces.
         * Long term would need debug info to populate names
         */
        func[i]->aux->name[0] = 'F';
        func[i]->aux->stack_depth = env->subprog_info[i].stack_depth;
        func[i]->jit_requested = 1;
        func[i]->aux->linfo = prog->aux->linfo;
        func[i]->aux->nr_linfo = prog->aux->nr_linfo;
        func[i]->aux->jited_linfo = prog->aux->jited_linfo;
        func[i]->aux->linfo_idx = env->subprog_info[i].linfo_idx;
        num_exentries = 0;
        insn = func[i]->insnsi;
        for (j = 0; j < func[i]->len; j++, insn++) {
            if (BPF_CLASS(insn->code) == BPF_LDX && BPF_MODE(insn->code) == BPF_PROBE_MEM) {
                num_exentries++;
            }
        }
        func[i]->aux->num_exentries = num_exentries;
        func[i]->aux->tail_call_reachable = env->subprog_info[i].tail_call_reachable;
        func[i] = bpf_int_jit_compile(func[i]);
        if (!func[i]->jited) {
            err = -ENOTSUPP;
            goto out_free;
        }
        cond_resched();
    }

    /* at this point all bpf functions were successfully JITed
     * now populate all bpf_calls with correct addresses and
     * run last pass of JIT
     */
    for (i = 0; i < env->subprog_cnt; i++) {
        insn = func[i]->insnsi;
        for (j = 0; j < func[i]->len; j++, insn++) {
            if (insn->code != (BPF_JMP | BPF_CALL) || insn->src_reg != BPF_PSEUDO_CALL) {
                continue;
            }
            subprog = insn->off;
            insn->imm = BPF_CAST_CALL(func[subprog]->bpf_func) - __bpf_call_base;
        }

        /* we use the aux data to keep a list of the start addresses
         * of the JITed images for each function in the program
         *
         * for some architectures, such as powerpc64, the imm field
         * might not be large enough to hold the offset of the start
         * address of the callee's JITed image from __bpf_call_base
         *
         * in such cases, we can lookup the start address of a callee
         * by using its subprog id, available from the off field of
         * the call instruction, as an index for this list
         */
        func[i]->aux->func = func;
        func[i]->aux->func_cnt = env->subprog_cnt;
    }
    for (i = 0; i < env->subprog_cnt; i++) {
        old_bpf_func = func[i]->bpf_func;
        tmp = bpf_int_jit_compile(func[i]);
        if (tmp != func[i] || func[i]->bpf_func != old_bpf_func) {
            verbose(env, "JIT doesn't support bpf-to-bpf calls\n");
            err = -ENOTSUPP;
            goto out_free;
        }
        cond_resched();
    }

    /* finally lock prog and jit images for all functions and
     * populate kallsysm
     */
    for (i = 0; i < env->subprog_cnt; i++) {
        bpf_prog_lock_ro(func[i]);
        bpf_prog_kallsyms_add(func[i]);
    }

    /* Last step: make now unused interpreter insns from main
     * prog consistent for later dump requests, so they can
     * later look the same as if they were interpreted only.
     */
    for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
        if (insn->code != (BPF_JMP | BPF_CALL) || insn->src_reg != BPF_PSEUDO_CALL) {
            continue;
        }
        insn->off = env->insn_aux_data[i].call_imm;
        subprog = find_subprog(env, i + insn->off + 1);
        insn->imm = subprog;
    }

    prog->jited = 1;
    prog->bpf_func = func[0]->bpf_func;
    prog->aux->func = func;
    prog->aux->func_cnt = env->subprog_cnt;
    bpf_prog_free_unused_jited_linfo(prog);
    return 0;
out_free:
    /* We failed JIT'ing, so at this point we need to unregister poke
     * descriptors from subprogs, so that kernel is not attempting to
     * patch it anymore as we're freeing the subprog JIT memory.
     */
    for (i = 0; i < prog->aux->size_poke_tab; i++) {
        map_ptr = prog->aux->poke_tab[i].tail_call.map;
        map_ptr->ops->map_poke_untrack(map_ptr, prog->aux);
    }
    /* At this point we're guaranteed that poke descriptors are not
     * live anymore. We can just unlink its descriptor table as it's
     * released with the main prog.
     */
    for (i = 0; i < env->subprog_cnt; i++) {
        if (!func[i]) {
            continue;
        }
        func[i]->aux->poke_tab = NULL;
        bpf_jit_free(func[i]);
    }
    kfree(func);
out_undo_insn:
    /* cleanup main prog to be interpreted */
    prog->jit_requested = 0;
    for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
        if (insn->code != (BPF_JMP | BPF_CALL) || insn->src_reg != BPF_PSEUDO_CALL) {
            continue;
        }
        insn->off = 0;
        insn->imm = env->insn_aux_data[i].call_imm;
    }
    bpf_prog_free_jited_linfo(prog);
    return err;
}

static int fixup_call_args(struct bpf_verifier_env *env)
{
#ifndef CONFIG_BPF_JIT_ALWAYS_ON
    struct bpf_prog *prog = env->prog;
    struct bpf_insn *insn = prog->insnsi;
    int i, depth;
#endif
    int err = 0;

    if (env->prog->jit_requested && !bpf_prog_is_dev_bound(env->prog->aux)) {
        err = jit_subprogs(env);
        if (err == 0) {
            return 0;
        }
        if (err == -EFAULT) {
            return err;
        }
    }
#ifndef CONFIG_BPF_JIT_ALWAYS_ON
    if (env->subprog_cnt > 1 && env->prog->aux->tail_call_reachable) {
        /* When JIT fails the progs with bpf2bpf calls and tail_calls
         * have to be rejected, since interpreter doesn't support them yet.
         */
        verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n");
        return -EINVAL;
    }
    for (i = 0; i < prog->len; i++, insn++) {
        if (insn->code != (BPF_JMP | BPF_CALL) || insn->src_reg != BPF_PSEUDO_CALL) {
            continue;
        }
        depth = get_callee_stack_depth(env, insn, i);
        if (depth < 0) {
            return depth;
        }
        bpf_patch_call_args(insn, depth);
    }
    err = 0;
#endif
    return err;
}

/* fixup insn->imm field of bpf_call instructions
 * and inline eligible helpers as explicit sequence of BPF instructions
 *
 * this function is called after eBPF program passed verification
 */
static int fixup_bpf_calls(struct bpf_verifier_env *env)
{
    struct bpf_prog *prog = env->prog;
    bool expect_blinding = bpf_jit_blinding_enabled(prog);
    struct bpf_insn *insn = prog->insnsi;
    const struct bpf_func_proto *fn;
    const int insn_cnt = prog->len;
    const struct bpf_map_ops *ops;
    struct bpf_insn_aux_data *aux;
    struct bpf_insn insn_buf[VERIFIER_SIXTEEN];
    struct bpf_prog *new_prog;
    struct bpf_map *map_ptr;
    int i, ret, cnt, delta = 0;

    for (i = 0; i < insn_cnt; i++, insn++) {
        if (insn->code == (BPF_ALU64 | BPF_MOD | BPF_X) || insn->code == (BPF_ALU64 | BPF_DIV | BPF_X) ||
            insn->code == (BPF_ALU | BPF_MOD | BPF_X) || insn->code == (BPF_ALU | BPF_DIV | BPF_X)) {
            bool is64 = BPF_CLASS(insn->code) == BPF_ALU64;
            bool isdiv = BPF_OP(insn->code) == BPF_DIV;
            struct bpf_insn *patchlet;
            struct bpf_insn chk_and_div[] = {
                /* [R,W]x div 0 -> 0 */
                BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) | BPF_JNE | BPF_K, insn->src_reg, 0, 2, 0),
                BPF_ALU32_REG(BPF_XOR, insn->dst_reg, insn->dst_reg),
                BPF_JMP_IMM(BPF_JA, 0, 0, 1),
                *insn,
            };
            struct bpf_insn chk_and_mod[] = {
                /* [R,W]x mod 0 -> [R,W]x */
                BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) | BPF_JEQ | BPF_K, insn->src_reg, 0, 1 + (is64 ? 0 : 1), 0),
                *insn,
                BPF_JMP_IMM(BPF_JA, 0, 0, 1),
                BPF_MOV32_REG(insn->dst_reg, insn->dst_reg),
            };

            patchlet = isdiv ? chk_and_div : chk_and_mod;
            cnt = isdiv ? ARRAY_SIZE(chk_and_div) : ARRAY_SIZE(chk_and_mod) - (is64 ? 0x2 : 0);

            new_prog = bpf_patch_insn_data(env, i + delta, patchlet, cnt);
            if (!new_prog) {
                return -ENOMEM;
            }

            delta += cnt - 1;
            env->prog = prog = new_prog;
            insn = new_prog->insnsi + i + delta;
            continue;
        }

        if (BPF_CLASS(insn->code) == BPF_LD && (BPF_MODE(insn->code) == BPF_ABS || BPF_MODE(insn->code) == BPF_IND)) {
            cnt = env->ops->gen_ld_abs(insn, insn_buf);
            if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
                verbose(env, "bpf verifier is misconfigured\n");
                return -EINVAL;
            }

            new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
            if (!new_prog) {
                return -ENOMEM;
            }

            delta += cnt - 1;
            env->prog = prog = new_prog;
            insn = new_prog->insnsi + i + delta;
            continue;
        }

        if (insn->code == (BPF_ALU64 | BPF_ADD | BPF_X) || insn->code == (BPF_ALU64 | BPF_SUB | BPF_X)) {
            const u8 code_add = BPF_ALU64 | BPF_ADD | BPF_X;
            const u8 code_sub = BPF_ALU64 | BPF_SUB | BPF_X;
            struct bpf_insn insn_buf_in[VERIFIER_SIXTEEN];
            struct bpf_insn *patch = &insn_buf_in[0];
            bool issrc, isneg, isimm;
            u32 off_reg;

            aux = &env->insn_aux_data[i + delta];
            if (!aux->alu_state || aux->alu_state == BPF_ALU_NON_POINTER) {
                continue;
            }

            isneg = aux->alu_state & BPF_ALU_NEG_VALUE;
            issrc = (aux->alu_state & BPF_ALU_SANITIZE) == BPF_ALU_SANITIZE_SRC;
            isimm = aux->alu_state & BPF_ALU_IMMEDIATE;

            off_reg = issrc ? insn->src_reg : insn->dst_reg;
            if (isimm) {
                *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit);
            } else {
                if (isneg) {
                    *patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1);
                }
                *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit);
                *patch++ = BPF_ALU64_REG(BPF_SUB, BPF_REG_AX, off_reg);
                *patch++ = BPF_ALU64_REG(BPF_OR, BPF_REG_AX, off_reg);
                *patch++ = BPF_ALU64_IMM(BPF_NEG, BPF_REG_AX, 0);
                *patch++ = BPF_ALU64_IMM(BPF_ARSH, BPF_REG_AX, VERIFIER_SIXTYTHREE);
                *patch++ = BPF_ALU64_REG(BPF_AND, BPF_REG_AX, off_reg);
            }
            if (!issrc) {
                *patch++ = BPF_MOV64_REG(insn->dst_reg, insn->src_reg);
            }
            insn->src_reg = BPF_REG_AX;
            if (isneg) {
                insn->code = insn->code == code_add ? code_sub : code_add;
            }
            *patch++ = *insn;
            if (issrc && isneg && !isimm) {
                *patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1);
            }
            cnt = patch - insn_buf_in;

            new_prog = bpf_patch_insn_data(env, i + delta, insn_buf_in, cnt);
            if (!new_prog) {
                return -ENOMEM;
            }

            delta += cnt - 1;
            env->prog = prog = new_prog;
            insn = new_prog->insnsi + i + delta;
            continue;
        }

        if (insn->code != (BPF_JMP | BPF_CALL)) {
            continue;
        }
        if (insn->src_reg == BPF_PSEUDO_CALL) {
            continue;
        }

        if (insn->imm == BPF_FUNC_get_route_realm) {
            prog->dst_needed = 1;
        }
        if (insn->imm == BPF_FUNC_get_prandom_u32) {
            bpf_user_rnd_init_once();
        }
        if (insn->imm == BPF_FUNC_override_return) {
            prog->kprobe_override = 1;
        }
        if (insn->imm == BPF_FUNC_tail_call) {
            /* If we tail call into other programs, we
             * cannot make any assumptions since they can
             * be replaced dynamically during runtime in
             * the program array.
             */
            prog->cb_access = 1;
            if (!allow_tail_call_in_subprogs(env)) {
                prog->aux->stack_depth = MAX_BPF_STACK;
            }
            prog->aux->max_pkt_offset = MAX_PACKET_OFF;

            /* mark bpf_tail_call as different opcode to avoid
             * conditional branch in the interpeter for every normal
             * call and to prevent accidental JITing by JIT compiler
             * that doesn't support bpf_tail_call yet
             */
            insn->imm = 0;
            insn->code = BPF_JMP | BPF_TAIL_CALL;

            aux = &env->insn_aux_data[i + delta];
            if (env->bpf_capable && !expect_blinding && prog->jit_requested && !bpf_map_key_poisoned(aux) &&
                !bpf_map_ptr_poisoned(aux) && !bpf_map_ptr_unpriv(aux)) {
                struct bpf_jit_poke_descriptor desc = {
                    .reason = BPF_POKE_REASON_TAIL_CALL,
                    .tail_call.map = BPF_MAP_PTR(aux->map_ptr_state),
                    .tail_call.key = bpf_map_key_immediate(aux),
                    .insn_idx = i + delta,
                };

                ret = bpf_jit_add_poke_descriptor(prog, &desc);
                if (ret < 0) {
                    verbose(env, "adding tail call poke descriptor failed\n");
                    return ret;
                }

                insn->imm = ret + 1;
                continue;
            }

            if (!bpf_map_ptr_unpriv(aux)) {
                continue;
            }

            /* instead of changing every JIT dealing with tail_call
             * emit two extra insns:
             * if (index >= max_entries) goto out;
             * index &= array->index_mask;
             * to avoid out-of-bounds cpu speculation
             */
            if (bpf_map_ptr_poisoned(aux)) {
                verbose(env, "tail_call abusing map_ptr\n");
                return -EINVAL;
            }

            map_ptr = BPF_MAP_PTR(aux->map_ptr_state);
            insn_buf[0x0] = BPF_JMP_IMM(BPF_JGE, BPF_REG_3, map_ptr->max_entries, 0x2);
            insn_buf[0x1] = BPF_ALU32_IMM(BPF_AND, BPF_REG_3, container_of(map_ptr, struct bpf_array, map)->index_mask);
            insn_buf[0x2] = *insn;
            cnt = VERIFIER_THREE;
            new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
            if (!new_prog) {
                return -ENOMEM;
            }

            delta += cnt - 1;
            env->prog = prog = new_prog;
            insn = new_prog->insnsi + i + delta;
            continue;
        }

        /* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup
         * and other inlining handlers are currently limited to 64 bit
         * only.
         */
        if (prog->jit_requested && BITS_PER_LONG == VERIFIER_SIXTYFOUR &&
            (insn->imm == BPF_FUNC_map_lookup_elem || insn->imm == BPF_FUNC_map_update_elem ||
             insn->imm == BPF_FUNC_map_delete_elem || insn->imm == BPF_FUNC_map_push_elem ||
             insn->imm == BPF_FUNC_map_pop_elem || insn->imm == BPF_FUNC_map_peek_elem)) {
            aux = &env->insn_aux_data[i + delta];
            if (bpf_map_ptr_poisoned(aux)) {
                goto patch_call_imm;
            }

            map_ptr = BPF_MAP_PTR(aux->map_ptr_state);
            ops = map_ptr->ops;
            if (insn->imm == BPF_FUNC_map_lookup_elem && ops->map_gen_lookup) {
                cnt = ops->map_gen_lookup(map_ptr, insn_buf);
                if (cnt == -EOPNOTSUPP) {
                    goto patch_map_ops_generic;
                }
                if (cnt <= 0 || cnt >= ARRAY_SIZE(insn_buf)) {
                    verbose(env, "bpf verifier is misconfigured\n");
                    return -EINVAL;
                }

                new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
                if (!new_prog) {
                    return -ENOMEM;
                }

                delta += cnt - 1;
                env->prog = prog = new_prog;
                insn = new_prog->insnsi + i + delta;
                continue;
            }

            BUILD_BUG_ON(!__same_type(ops->map_lookup_elem, (void *(*)(struct bpf_map * map, void *key)) NULL));
            BUILD_BUG_ON(!__same_type(ops->map_delete_elem, (int (*)(struct bpf_map * map, void *key)) NULL));
            BUILD_BUG_ON(!__same_type(ops->map_update_elem,
                                      (int (*)(struct bpf_map * map, void *key, void *value, u64 flags)) NULL));
            BUILD_BUG_ON(
                !__same_type(ops->map_push_elem, (int (*)(struct bpf_map * map, void *value, u64 flags)) NULL));
            BUILD_BUG_ON(!__same_type(ops->map_pop_elem, (int (*)(struct bpf_map * map, void *value)) NULL));
            BUILD_BUG_ON(!__same_type(ops->map_peek_elem, (int (*)(struct bpf_map * map, void *value)) NULL));
        patch_map_ops_generic:
            switch (insn->imm) {
                case BPF_FUNC_map_lookup_elem:
                    insn->imm = BPF_CAST_CALL(ops->map_lookup_elem) - __bpf_call_base;
                    continue;
                case BPF_FUNC_map_update_elem:
                    insn->imm = BPF_CAST_CALL(ops->map_update_elem) - __bpf_call_base;
                    continue;
                case BPF_FUNC_map_delete_elem:
                    insn->imm = BPF_CAST_CALL(ops->map_delete_elem) - __bpf_call_base;
                    continue;
                case BPF_FUNC_map_push_elem:
                    insn->imm = BPF_CAST_CALL(ops->map_push_elem) - __bpf_call_base;
                    continue;
                case BPF_FUNC_map_pop_elem:
                    insn->imm = BPF_CAST_CALL(ops->map_pop_elem) - __bpf_call_base;
                    continue;
                case BPF_FUNC_map_peek_elem:
                    insn->imm = BPF_CAST_CALL(ops->map_peek_elem) - __bpf_call_base;
                    continue;
                default:
                    break;
            }

            goto patch_call_imm;
        }

        if (prog->jit_requested && BITS_PER_LONG == VERIFIER_SIXTYFOUR && insn->imm == BPF_FUNC_jiffies64) {
            struct bpf_insn ld_jiffies_addr[2] = {
                BPF_LD_IMM64(BPF_REG_0, (unsigned long)&jiffies),
            };

            insn_buf[0x0] = ld_jiffies_addr[0];
            insn_buf[0x1] = ld_jiffies_addr[1];
            insn_buf[0x2] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_0, 0);
            cnt = VERIFIER_THREE;

            new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
            if (!new_prog) {
                return -ENOMEM;
            }

            delta += cnt - 1;
            env->prog = prog = new_prog;
            insn = new_prog->insnsi + i + delta;
            continue;
        }

    patch_call_imm:
        fn = env->ops->get_func_proto(insn->imm, env->prog);
        /* all functions that have prototype and verifier allowed
         * programs to call them, must be real in-kernel functions
         */
        if (!fn->func) {
            verbose(env, "kernel subsystem misconfigured func %s#%d\n", func_id_name(insn->imm), insn->imm);
            return -EFAULT;
        }
        insn->imm = fn->func - __bpf_call_base;
    }

    /* Since poke tab is now finalized, publish aux to tracker. */
    for (i = 0; i < prog->aux->size_poke_tab; i++) {
        map_ptr = prog->aux->poke_tab[i].tail_call.map;
        if (!map_ptr->ops->map_poke_track || !map_ptr->ops->map_poke_untrack || !map_ptr->ops->map_poke_run) {
            verbose(env, "bpf verifier is misconfigured\n");
            return -EINVAL;
        }

        ret = map_ptr->ops->map_poke_track(map_ptr, prog->aux);
        if (ret < 0) {
            verbose(env, "tracking tail call prog failed\n");
            return ret;
        }
    }

    return 0;
}

static void free_states(struct bpf_verifier_env *env)
{
    struct bpf_verifier_state_list *sl, *sln;
    int i;

    sl = env->free_list;
    while (sl) {
        sln = sl->next;
        free_verifier_state(&sl->state, false);
        kfree(sl);
        sl = sln;
    }
    env->free_list = NULL;

    if (!env->explored_states) {
        return;
    }

    for (i = 0; i < state_htab_size(env); i++) {
        sl = env->explored_states[i];

        while (sl) {
            sln = sl->next;
            free_verifier_state(&sl->state, false);
            kfree(sl);
            sl = sln;
        }
        env->explored_states[i] = NULL;
    }
}

static int do_check_common(struct bpf_verifier_env *env, int subprog)
{
    bool pop_log = !(env->log.level & BPF_LOG_LEVEL2);
    struct bpf_verifier_state *state;
    struct bpf_reg_state *regs;
    int ret, i;

    env->prev_linfo = NULL;
    env->pass_cnt++;

    state = kzalloc(sizeof(struct bpf_verifier_state), GFP_KERNEL);
    if (!state) {
        return -ENOMEM;
    }
    state->curframe = 0;
    state->speculative = false;
    state->branches = 1;
    state->frame[0] = kzalloc(sizeof(struct bpf_func_state), GFP_KERNEL);
    if (!state->frame[0]) {
        kfree(state);
        return -ENOMEM;
    }
    env->cur_state = state;
    init_func_state(env, state->frame[0], BPF_MAIN_FUNC /* callsite */, 0 /* frameno */, subprog);

    regs = state->frame[state->curframe]->regs;
    if (subprog || env->prog->type == BPF_PROG_TYPE_EXT) {
        ret = btf_prepare_func_args(env, subprog, regs);
        if (ret) {
            goto out;
        }
        for (i = BPF_REG_1; i <= BPF_REG_5; i++) {
            if (regs[i].type == PTR_TO_CTX) {
                mark_reg_known_zero(env, regs, i);
            } else if (regs[i].type == SCALAR_VALUE) {
                mark_reg_unknown(env, regs, i);
            }
        }
    } else {
        /* 1st arg to a function */
        regs[BPF_REG_1].type = PTR_TO_CTX;
        mark_reg_known_zero(env, regs, BPF_REG_1);
        ret = btf_check_func_arg_match(env, subprog, regs);
        if (ret == -EFAULT) {
            /* unlikely verifier bug. abort.
             * ret == 0 and ret < 0 are sadly acceptable for
             * main() function due to backward compatibility.
             * Like socket filter program may be written as:
             * int bpf_prog(struct pt_regs *ctx)
             * and never dereference that ctx in the program.
             * 'struct pt_regs' is a type mismatch for socket
             * filter that should be using 'struct __sk_buff'.
             */
            goto out;
        }
    }

    ret = do_check(env);
out:
    /* check for NULL is necessary, since cur_state can be freed inside
     * do_check() under memory pressure.
     */
    if (env->cur_state) {
        free_verifier_state(env->cur_state, true);
        env->cur_state = NULL;
    }
    while (!pop_stack(env, NULL, NULL, false)) {
        ;
    }
    if (!ret && pop_log) {
        bpf_vlog_reset(&env->log, 0);
    }
    free_states(env);
    return ret;
}

/* Verify all global functions in a BPF program one by one based on their BTF.
 * All global functions must pass verification. Otherwise the whole program is rejected.
 * Consider:
 * int bar(int);
 * int foo(int f)
 * {
 *    return bar(f);
 * }
 * int bar(int b)
 * {
 *    ...
 * }
 * foo() will be verified first for R1=any_scalar_value. During verification it
 * will be assumed that bar() already verified successfully and call to bar()
 * from foo() will be checked for type match only. Later bar() will be verified
 * independently to check that it's safe for R1=any_scalar_value.
 */
static int do_check_subprogs(struct bpf_verifier_env *env)
{
    struct bpf_prog_aux *aux = env->prog->aux;
    int i, ret;

    if (!aux->func_info) {
        return 0;
    }

    for (i = 1; i < env->subprog_cnt; i++) {
        if (aux->func_info_aux[i].linkage != BTF_FUNC_GLOBAL) {
            continue;
        }
        env->insn_idx = env->subprog_info[i].start;
        WARN_ON_ONCE(env->insn_idx == 0);
        ret = do_check_common(env, i);
        if (ret) {
            return ret;
        } else if (env->log.level & BPF_LOG_LEVEL) {
            verbose(env, "Func#%d is safe for any args that match its prototype\n", i);
        }
    }
    return 0;
}

static int do_check_main(struct bpf_verifier_env *env)
{
    int ret;

    env->insn_idx = 0;
    ret = do_check_common(env, 0);
    if (!ret) {
        env->prog->aux->stack_depth = env->subprog_info[0].stack_depth;
    }
    return ret;
}

static void print_verification_stats(struct bpf_verifier_env *env)
{
    int i;

    if (env->log.level & BPF_LOG_STATS) {
        verbose(env, "verification time %lld usec\n", div_u64(env->verification_time, VERIFIER_ONETHOUSAND));
        verbose(env, "stack depth ");
        for (i = 0; i < env->subprog_cnt; i++) {
            u32 depth = env->subprog_info[i].stack_depth;

            verbose(env, "%d", depth);
            if (i + 1 < env->subprog_cnt) {
                verbose(env, "+");
            }
        }
        verbose(env, "\n");
    }
    verbose(env,
            "processed %d insns (limit %d) max_states_per_insn %d "
            "total_states %d peak_states %d mark_read %d\n",
            env->insn_processed, BPF_COMPLEXITY_LIMIT_INSNS, env->max_states_per_insn, env->total_states,
            env->peak_states, env->longest_mark_read_walk);
}

static int check_struct_ops_btf_id(struct bpf_verifier_env *env)
{
    const struct btf_type *t, *func_proto;
    const struct bpf_struct_ops *st_ops;
    const struct btf_member *member;
    struct bpf_prog *prog = env->prog;
    u32 btf_id, member_idx;
    const char *mname;

    if (!prog->gpl_compatible) {
        verbose(env, "struct ops programs must have a GPL compatible license\n");
        return -EINVAL;
    }

    btf_id = prog->aux->attach_btf_id;
    st_ops = bpf_struct_ops_find(btf_id);
    if (!st_ops) {
        verbose(env, "attach_btf_id %u is not a supported struct\n", btf_id);
        return -ENOTSUPP;
    }

    t = st_ops->type;
    member_idx = prog->expected_attach_type;
    if (member_idx >= btf_type_vlen(t)) {
        verbose(env, "attach to invalid member idx %u of struct %s\n", member_idx, st_ops->name);
        return -EINVAL;
    }

    member = &btf_type_member(t)[member_idx];
    mname = btf_name_by_offset(btf_vmlinux, member->name_off);
    func_proto = btf_type_resolve_func_ptr(btf_vmlinux, member->type, NULL);
    if (!func_proto) {
        verbose(env, "attach to invalid member %s(@idx %u) of struct %s\n", mname, member_idx, st_ops->name);
        return -EINVAL;
    }

    if (st_ops->check_member) {
        int err = st_ops->check_member(t, member);
        if (err) {
            verbose(env, "attach to unsupported member %s of struct %s\n", mname, st_ops->name);
            return err;
        }
    }

    prog->aux->attach_func_proto = func_proto;
    prog->aux->attach_func_name = mname;
    env->ops = st_ops->verifier_ops;

    return 0;
}
#define SECURITY_PREFIX "security_"

static int check_attach_modify_return(unsigned long addr, const char *func_name)
{
    if (within_error_injection_list(addr) || !strncmp(SECURITY_PREFIX, func_name, sizeof(SECURITY_PREFIX) - 1)) {
        return 0;
    }
    return -EINVAL;
}

/* non exhaustive list of sleepable bpf_lsm_*() functions */
BTF_SET_START(btf_sleepable_lsm_hooks)
#ifdef CONFIG_BPF_LSM
BTF_ID(func, bpf_lsm_bprm_committed_creds)
#else
BTF_ID_UNUSED
#endif
BTF_SET_END(btf_sleepable_lsm_hooks)

static int check_sleepable_lsm_hook(u32 btf_id)
{
    return btf_id_set_contains(&btf_sleepable_lsm_hooks, btf_id);
}

/* list of non-sleepable functions that are otherwise on
 * ALLOW_ERROR_INJECTION list
 */
BTF_SET_START(btf_non_sleepable_error_inject)
/* Three functions below can be called from sleepable and non-sleepable context.
 * Assume non-sleepable from bpf safety point of view.
 */
BTF_ID(func, __add_to_page_cache_locked)
BTF_ID(func, should_fail_alloc_page)
BTF_ID(func, should_failslab)
BTF_SET_END(btf_non_sleepable_error_inject)

static int check_non_sleepable_error_inject(u32 btf_id)
{
    return btf_id_set_contains(&btf_non_sleepable_error_inject, btf_id);
}

int bpf_check_attach_target(struct bpf_verifier_log *log, const struct bpf_prog *prog, const struct bpf_prog *tgt_prog,
                            u32 btf_id, struct bpf_attach_target_info *tgt_info)
{
    bool prog_extension = prog->type == BPF_PROG_TYPE_EXT;
    const char prefix[] = "btf_trace_";
    int ret = 0, subprog = -1, i;
    const struct btf_type *t;
    bool conservative = true;
    const char *tname;
    struct btf *btf;
    long addr = 0;

    if (!btf_id) {
        bpf_log(log, "Tracing programs must provide btf_id\n");
        return -EINVAL;
    }
    btf = tgt_prog ? tgt_prog->aux->btf : btf_vmlinux;
    if (!btf) {
        bpf_log(log, "FENTRY/FEXIT program can only be attached to another program annotated with BTF\n");
        return -EINVAL;
    }
    t = btf_type_by_id(btf, btf_id);
    if (!t) {
        bpf_log(log, "attach_btf_id %u is invalid\n", btf_id);
        return -EINVAL;
    }
    tname = btf_name_by_offset(btf, t->name_off);
    if (!tname) {
        bpf_log(log, "attach_btf_id %u doesn't have a name\n", btf_id);
        return -EINVAL;
    }
    if (tgt_prog) {
        struct bpf_prog_aux *aux = tgt_prog->aux;

        for (i = 0; i < aux->func_info_cnt; i++) {
            if (aux->func_info[i].type_id == btf_id) {
                subprog = i;
                break;
            }
        }
        if (subprog == -1) {
            bpf_log(log, "Subprog %s doesn't exist\n", tname);
            return -EINVAL;
        }
        conservative = aux->func_info_aux[subprog].unreliable;
        if (prog_extension) {
            if (conservative) {
                bpf_log(log, "Cannot replace static functions\n");
                return -EINVAL;
            }
            if (!prog->jit_requested) {
                bpf_log(log, "Extension programs should be JITed\n");
                return -EINVAL;
            }
        }
        if (!tgt_prog->jited) {
            bpf_log(log, "Can attach to only JITed progs\n");
            return -EINVAL;
        }
        if (tgt_prog->type == prog->type) {
            /* Cannot fentry/fexit another fentry/fexit program.
             * Cannot attach program extension to another extension.
             * It's ok to attach fentry/fexit to extension program.
             */
            bpf_log(log, "Cannot recursively attach\n");
            return -EINVAL;
        }
        if (tgt_prog->type == BPF_PROG_TYPE_TRACING && prog_extension &&
            (tgt_prog->expected_attach_type == BPF_TRACE_FENTRY || tgt_prog->expected_attach_type == BPF_TRACE_FEXIT)) {
            /* Program extensions can extend all program types
             * except fentry/fexit. The reason is the following.
             * The fentry/fexit programs are used for performance
             * analysis, stats and can be attached to any program
             * type except themselves. When extension program is
             * replacing XDP function it is necessary to allow
             * performance analysis of all functions. Both original
             * XDP program and its program extension. Hence
             * attaching fentry/fexit to BPF_PROG_TYPE_EXT is
             * allowed. If extending of fentry/fexit was allowed it
             * would be possible to create long call chain
             * fentry->extension->fentry->extension beyond
             * reasonable stack size. Hence extending fentry is not
             * allowed.
             */
            bpf_log(log, "Cannot extend fentry/fexit\n");
            return -EINVAL;
        }
    } else {
        if (prog_extension) {
            bpf_log(log, "Cannot replace kernel functions\n");
            return -EINVAL;
        }
    }

    switch (prog->expected_attach_type) {
        case BPF_TRACE_RAW_TP:
            if (tgt_prog) {
                bpf_log(log, "Only FENTRY/FEXIT progs are attachable to another BPF prog\n");
                return -EINVAL;
            }
            if (!btf_type_is_typedef(t)) {
                bpf_log(log, "attach_btf_id %u is not a typedef\n", btf_id);
                return -EINVAL;
            }
            if (strncmp(prefix, tname, sizeof(prefix) - 1)) {
                bpf_log(log, "attach_btf_id %u points to wrong type name %s\n", btf_id, tname);
                return -EINVAL;
            }
            tname += sizeof(prefix) - 1;
            t = btf_type_by_id(btf, t->type);
            if (!btf_type_is_ptr(t)) {
                /* should never happen in valid vmlinux build */
                return -EINVAL;
            }
            t = btf_type_by_id(btf, t->type);
            if (!btf_type_is_func_proto(t)) {
                /* should never happen in valid vmlinux build */
                return -EINVAL;
            }

            break;
        case BPF_TRACE_ITER:
            if (!btf_type_is_func(t)) {
                bpf_log(log, "attach_btf_id %u is not a function\n", btf_id);
                return -EINVAL;
            }
            t = btf_type_by_id(btf, t->type);
            if (!btf_type_is_func_proto(t)) {
                return -EINVAL;
            }
            ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel);
            if (ret) {
                return ret;
            }
            break;
        default:
            if (!prog_extension) {
                return -EINVAL;
            }
            fallthrough;
        case BPF_MODIFY_RETURN:
        case BPF_LSM_MAC:
        case BPF_TRACE_FENTRY:
        case BPF_TRACE_FEXIT:
            if (!btf_type_is_func(t)) {
                bpf_log(log, "attach_btf_id %u is not a function\n", btf_id);
                return -EINVAL;
            }
            if (prog_extension && btf_check_type_match(log, prog, btf, t)) {
                return -EINVAL;
            }
            t = btf_type_by_id(btf, t->type);
            if (!btf_type_is_func_proto(t)) {
                return -EINVAL;
            }

            if ((prog->aux->saved_dst_prog_type || prog->aux->saved_dst_attach_type) &&
                (!tgt_prog || prog->aux->saved_dst_prog_type != tgt_prog->type ||
                 prog->aux->saved_dst_attach_type != tgt_prog->expected_attach_type)) {
                return -EINVAL;
            }

            if (tgt_prog && conservative) {
                t = NULL;
            }

            ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel);
            if (ret < 0) {
                return ret;
            }

            if (tgt_prog) {
                if (subprog == 0) {
                    addr = (long)tgt_prog->bpf_func;
                } else {
                    addr = (long)tgt_prog->aux->func[subprog]->bpf_func;
                }
            } else {
                addr = kallsyms_lookup_name(tname);
                if (!addr) {
                    bpf_log(log, "The address of function %s cannot be found\n", tname);
                    return -ENOENT;
                }
            }

            if (prog->aux->sleepable) {
                ret = -EINVAL;
                switch (prog->type) {
                    case BPF_PROG_TYPE_TRACING:
                        /* fentry/fexit/fmod_ret progs can be sleepable only if they are
                         * attached to ALLOW_ERROR_INJECTION and are not in denylist.
                         */
                        if (!check_non_sleepable_error_inject(btf_id) && within_error_injection_list(addr)) {
                            ret = 0;
                        }
                        break;
                    case BPF_PROG_TYPE_LSM:
                        /* LSM progs check that they are attached to bpf_lsm_*() funcs.
                         * Only some of them are sleepable.
                         */
                        if (check_sleepable_lsm_hook(btf_id)) {
                            ret = 0;
                        }
                        break;
                    default:
                        break;
                }
                if (ret) {
                    bpf_log(log, "%s is not sleepable\n", tname);
                    return ret;
                }
            } else if (prog->expected_attach_type == BPF_MODIFY_RETURN) {
                if (tgt_prog) {
                    bpf_log(log, "can't modify return codes of BPF programs\n");
                    return -EINVAL;
                }
                ret = check_attach_modify_return(addr, tname);
                if (ret) {
                    bpf_log(log, "%s() is not modifiable\n", tname);
                    return ret;
                }
            }

            break;
    }
    tgt_info->tgt_addr = addr;
    tgt_info->tgt_name = tname;
    tgt_info->tgt_type = t;
    return 0;
}

static int check_attach_btf_id(struct bpf_verifier_env *env)
{
    struct bpf_prog *prog = env->prog;
    struct bpf_prog *tgt_prog = prog->aux->dst_prog;
    struct bpf_attach_target_info tgt_info = {};
    u32 btf_id = prog->aux->attach_btf_id;
    struct bpf_trampoline *tr;
    int ret;
    u64 key;

    if (prog->aux->sleepable && prog->type != BPF_PROG_TYPE_TRACING && prog->type != BPF_PROG_TYPE_LSM) {
        verbose(env, "Only fentry/fexit/fmod_ret and lsm programs can be sleepable\n");
        return -EINVAL;
    }

    if (prog->type == BPF_PROG_TYPE_STRUCT_OPS) {
        return check_struct_ops_btf_id(env);
    }

    if (prog->type != BPF_PROG_TYPE_TRACING && prog->type != BPF_PROG_TYPE_LSM && prog->type != BPF_PROG_TYPE_EXT) {
        return 0;
    }

    ret = bpf_check_attach_target(&env->log, prog, tgt_prog, btf_id, &tgt_info);
    if (ret) {
        return ret;
    }

    if (tgt_prog && prog->type == BPF_PROG_TYPE_EXT) {
        /* to make freplace equivalent to their targets, they need to
         * inherit env->ops and expected_attach_type for the rest of the
         * verification
         */
        env->ops = bpf_verifier_ops[tgt_prog->type];
        prog->expected_attach_type = tgt_prog->expected_attach_type;
    }

    /* store info about the attachment target that will be used later */
    prog->aux->attach_func_proto = tgt_info.tgt_type;
    prog->aux->attach_func_name = tgt_info.tgt_name;

    if (tgt_prog) {
        prog->aux->saved_dst_prog_type = tgt_prog->type;
        prog->aux->saved_dst_attach_type = tgt_prog->expected_attach_type;
    }

    if (prog->expected_attach_type == BPF_TRACE_RAW_TP) {
        prog->aux->attach_btf_trace = true;
        return 0;
    } else if (prog->expected_attach_type == BPF_TRACE_ITER) {
        if (!bpf_iter_prog_supported(prog)) {
            return -EINVAL;
        }
        return 0;
    }

    if (prog->type == BPF_PROG_TYPE_LSM) {
        ret = bpf_lsm_verify_prog(&env->log, prog);
        if (ret < 0) {
            return ret;
        }
    }

    key = bpf_trampoline_compute_key(tgt_prog, btf_id);
    tr = bpf_trampoline_get(key, &tgt_info);
    if (!tr) {
        return -ENOMEM;
    }

    prog->aux->dst_trampoline = tr;
    return 0;
}

struct btf *bpf_get_btf_vmlinux(void)
{
    if (!btf_vmlinux && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
        mutex_lock(&bpf_verifier_lock);
        if (!btf_vmlinux) {
            btf_vmlinux = btf_parse_vmlinux();
        }
        mutex_unlock(&bpf_verifier_lock);
    }
    return btf_vmlinux;
}

int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, union bpf_attr __user *uattr)
{
    u64 start_time = ktime_get_ns();
    struct bpf_verifier_env *env;
    struct bpf_verifier_log *log;
    int i, len, ret = -EINVAL;
    bool is_priv;

    /* no program is valid */
    if (ARRAY_SIZE(bpf_verifier_ops) == 0) {
        return -EINVAL;
    }

    /* 'struct bpf_verifier_env' can be global, but since it's not small,
     * allocate/free it every time bpf_check() is called
     */
    env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
    if (!env) {
        return -ENOMEM;
    }
    log = &env->log;

    len = (*prog)->len;
    env->insn_aux_data = vzalloc(array_size(sizeof(struct bpf_insn_aux_data), len));
    ret = -ENOMEM;
    if (!env->insn_aux_data) {
        goto err_free_env;
    }
    for (i = 0; i < len; i++) {
        env->insn_aux_data[i].orig_idx = i;
    }
    env->prog = *prog;
    env->ops = bpf_verifier_ops[env->prog->type];
    is_priv = bpf_capable();

    bpf_get_btf_vmlinux();

    /* grab the mutex to protect few globals used by verifier */
    if (!is_priv) {
        mutex_lock(&bpf_verifier_lock);
    }

    if (attr->log_level || attr->log_buf || attr->log_size) {
        /* user requested verbose verifier output
         * and supplied buffer to store the verification trace
         */
        log->level = attr->log_level;
        log->ubuf = (char __user *)(unsigned long)attr->log_buf;
        log->len_total = attr->log_size;

        /* log attributes have to be sane */
        if (!bpf_verifier_log_attr_valid(log)) {
            ret = -EINVAL;
            goto err_unlock;
        }
    }

    if (IS_ERR(btf_vmlinux)) {
        /* Either gcc or pahole or kernel are broken. */
        verbose(env, "in-kernel BTF is malformed\n");
        ret = PTR_ERR(btf_vmlinux);
        goto skip_full_check;
    }

    env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT);
    if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
        env->strict_alignment = true;
    }
    if (attr->prog_flags & BPF_F_ANY_ALIGNMENT) {
        env->strict_alignment = false;
    }

    env->allow_ptr_leaks = bpf_allow_ptr_leaks();
    env->allow_uninit_stack = bpf_allow_uninit_stack();
    env->allow_ptr_to_map_access = bpf_allow_ptr_to_map_access();
    env->bypass_spec_v1 = bpf_bypass_spec_v1();
    env->bypass_spec_v4 = bpf_bypass_spec_v4();
    env->bpf_capable = bpf_capable();

    if (is_priv) {
        env->test_state_freq = attr->prog_flags & BPF_F_TEST_STATE_FREQ;
    }

    env->explored_states = kvcalloc(state_htab_size(env), sizeof(struct bpf_verifier_state_list *), GFP_USER);
    ret = -ENOMEM;
    if (!env->explored_states) {
        goto skip_full_check;
    }

    ret = check_subprogs(env);
    if (ret < 0) {
        goto skip_full_check;
    }

    ret = check_btf_info(env, attr, uattr);
    if (ret < 0) {
        goto skip_full_check;
    }

    ret = check_attach_btf_id(env);
    if (ret) {
        goto skip_full_check;
    }

    ret = resolve_pseudo_ldimm64(env);
    if (ret < 0) {
        goto skip_full_check;
    }

    if (bpf_prog_is_dev_bound(env->prog->aux)) {
        ret = bpf_prog_offload_verifier_prep(env->prog);
        if (ret) {
            goto skip_full_check;
        }
    }

    ret = check_cfg(env);
    if (ret < 0) {
        goto skip_full_check;
    }

    ret = do_check_subprogs(env);
    ret = ret ?: do_check_main(env);

    if (ret == 0 && bpf_prog_is_dev_bound(env->prog->aux)) {
        ret = bpf_prog_offload_finalize(env);
    }

skip_full_check:
    kvfree(env->explored_states);

    if (ret == 0) {
        ret = check_max_stack_depth(env);
    }

    /* instruction rewrites happen after this point */
    if (is_priv) {
        if (ret == 0) {
            opt_hard_wire_dead_code_branches(env);
        }
        if (ret == 0) {
            ret = opt_remove_dead_code(env);
        }
        if (ret == 0) {
            ret = opt_remove_nops(env);
        }
    } else {
        if (ret == 0) {
            sanitize_dead_code(env);
        }
    }

    if (ret == 0) {
        /* program is valid, convert *(u32*)(ctx + off) accesses */
        ret = convert_ctx_accesses(env);
    }

    if (ret == 0) {
        ret = fixup_bpf_calls(env);
    }

    /* do 32-bit optimization after insn patching has done so those patched
     * insns could be handled correctly.
     */
    if (ret == 0 && !bpf_prog_is_dev_bound(env->prog->aux)) {
        ret = opt_subreg_zext_lo32_rnd_hi32(env, attr);
        env->prog->aux->verifier_zext = bpf_jit_needs_zext() ? !ret : false;
    }

    if (ret == 0) {
        ret = fixup_call_args(env);
    }

    env->verification_time = ktime_get_ns() - start_time;
    print_verification_stats(env);

    if (log->level && bpf_verifier_log_full(log)) {
        ret = -ENOSPC;
    }
    if (log->level && !log->ubuf) {
        ret = -EFAULT;
        goto err_release_maps;
    }

    if (ret == 0 && env->used_map_cnt) {
        /* if program passed verifier, update used_maps in bpf_prog_info */
        env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt, sizeof(env->used_maps[0]), GFP_KERNEL);

        if (!env->prog->aux->used_maps) {
            ret = -ENOMEM;
            goto err_release_maps;
        }

        memcpy(env->prog->aux->used_maps, env->used_maps, sizeof(env->used_maps[0]) * env->used_map_cnt);
        env->prog->aux->used_map_cnt = env->used_map_cnt;

        /* program is valid. Convert pseudo bpf_ld_imm64 into generic
         * bpf_ld_imm64 instructions
         */
        convert_pseudo_ld_imm64(env);
    }

    if (ret == 0) {
        adjust_btf_func(env);
    }

err_release_maps:
    if (!env->prog->aux->used_maps) {
        /* if we didn't copy map pointers into bpf_prog_info, release
         * them now. Otherwise free_used_maps() will release them.
         */
        release_maps(env);
    }

    /* extension progs temporarily inherit the attach_type of their targets
       for verification purposes, so set it back to zero before returning
     */
    if (env->prog->type == BPF_PROG_TYPE_EXT) {
        env->prog->expected_attach_type = 0;
    }

    *prog = env->prog;
err_unlock:
    if (!is_priv) {
        mutex_unlock(&bpf_verifier_lock);
    }
    vfree(env->insn_aux_data);
err_free_env:
    kfree(env);
    return ret;
}
